diff --git a/nested/src/grid/flatten.rs b/nested/src/grid/flatten.rs
index 92c2dc2..b97e746 100644
--- a/nested/src/grid/flatten.rs
+++ b/nested/src/grid/flatten.rs
@@ -1,18 +1,19 @@
 use {
     std::{
         sync::Arc,
+        cmp::max,
         collections::HashMap
     },
     std::sync::RwLock,
     cgmath::{Point2, Vector2},
     crate::{
         core::{
-            View, Observer, ObserverBroadcast, ObserverExt,
+            View, Observer, ObserverBroadcast,
             ViewPort, InnerViewPort, OuterViewPort,
             port::UpdateTask
         },
         grid::{GridView, GridWindowIterator},
-        index::IndexView,
+        index::{IndexArea, IndexView},
         projection::ProjectionHelper
     }
 };
@@ -48,7 +49,7 @@ where Item: 'static
 impl<Item> View for Flatten<Item>
 where Item: 'static
 {
-    type Msg = Point2<i16>;
+    type Msg = IndexArea<Point2<i16>>;
 }
 
 impl<Item> IndexView<Point2<i16>> for Flatten<Item>
@@ -57,13 +58,15 @@ where Item: 'static
     type Item = Item;
 
     fn get(&self, idx: &Point2<i16>) -> Option<Self::Item> {
-        let chunk_idx = self.get_chunk_idx(*idx)?;        
-        let chunk = self.chunks.get(&chunk_idx)?;        
+        let chunk_idx = self.get_chunk_idx(*idx)?;
+        let chunk = self.chunks.get(&chunk_idx)?;
         chunk.view.get(&(*idx - chunk.offset))
     }
 
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        Some(GridWindowIterator::from(Point2::new(0, 0) .. self.limit).collect())
+    fn area(&self) -> IndexArea<Point2<i16>> {
+        IndexArea::Range(
+            Point2::new(0, 0) ..= self.limit
+        )
     }
 }
 
@@ -83,8 +86,10 @@ where Item: 'static
                 top: proj_helper.new_index_arg(
                     Point2::new(-1, -1),
                     top_port,
-                    |s: &mut Self, chunk_idx| {
-                        s.update_chunk(*chunk_idx);
+                    |s: &mut Self, chunk_area| {
+                        for chunk_idx in chunk_area.iter() {
+                            s.update_chunk(chunk_idx);
+                        }
                     }
                 ),
                 chunks: HashMap::new(),
@@ -104,20 +109,26 @@ where Item: 'static
             let view = self.proj_helper.new_index_arg(
                 chunk_idx,
                 chunk_port.clone(),
-                move |s: &mut Self, idx| {
+                move |s: &mut Self, area| {
                     if let Some(chunk) = s.chunks.get(&chunk_idx) {
-                        if chunk.limit != chunk.view.range().end {
+                        if chunk.limit != *chunk.view.area().range().end() {
                             s.update_all_offsets();
                         }
                     }
+
                     if let Some(chunk) = s.chunks.get(&chunk_idx) {
-                        s.cast.notify(&(idx + chunk.offset));
+                        s.cast.notify(
+                            &area.map(|pt| pt + chunk.offset)
+                        );
                     }
                 }
             );
 
             if let Some(chunk) = self.chunks.get_mut(&chunk_idx) {
                 chunk.view = view;
+                self.cast.notify(
+                    &chunk.view.area().map(|pt| pt + chunk.offset)
+                );
             } else {
                 self.chunks.insert(
                     chunk_idx,
@@ -129,94 +140,91 @@ where Item: 'static
                 );
             }
 
-            chunk_port.0.update();
             self.update_all_offsets();
-            chunk_port.0.update();
         } else {
             self.proj_helper.remove_arg(&chunk_idx);
 
-            let mut dirty_idx = Vec::new();
-            if let Some(chunk) = self.chunks.get_mut(&chunk_idx) {
-                dirty_idx.extend(
-                    GridWindowIterator::from(
-                        Point2::new(chunk.offset.x, chunk.offset.y)
-                            .. Point2::new(chunk.offset.x + chunk.limit.x, chunk.offset.y + chunk.limit.y))
-                );
+            if let Some(chunk) = self.chunks.remove(&chunk_idx) {
+                self.update_all_offsets();
             }
-
-            self.chunks.remove(&chunk_idx);
-            self.cast.notify_each(dirty_idx);
-            self.update_all_offsets();
         }
     }
 
     /// recalculate all chunk offsets
     /// and update size of flattened grid
     fn update_all_offsets(&mut self) {
-        let mut dirty_idx = Vec::new();
+        let top_range = self.top.area().range();
+        let mut col_widths = vec![0 as i16; (top_range.end().x+1) as usize];
+        let mut row_heights = vec![0 as i16; (top_range.end().y+1) as usize];
 
-        let top_range = self.top.range();
-        let mut col_widths = vec![0 as i16; (top_range.end.x) as usize];
-        let mut row_heights = vec![0 as i16; (top_range.end.y) as usize];
-
-        for chunk_idx in GridWindowIterator::from(self.top.range()) {
+        for chunk_idx in GridWindowIterator::from(top_range.clone()) {
             if let Some(chunk) = self.chunks.get_mut(&chunk_idx) {
-                let lim = chunk.view.range().end;
-                col_widths[chunk_idx.x as usize] = std::cmp::max(col_widths[chunk_idx.x as usize], lim.x);
-                row_heights[chunk_idx.y as usize] = std::cmp::max(row_heights[chunk_idx.y as usize], lim.y);
+                let chunk_range = chunk.view.area().range();
+                let lim = *chunk_range.end();
+
+                col_widths[chunk_idx.x as usize] =
+                    max(
+                        col_widths[chunk_idx.x as usize],
+                        if lim.x < 0 { 0 } else { lim.x+1 }
+                    );
+                row_heights[chunk_idx.y as usize] =
+                    max(
+                        row_heights[chunk_idx.y as usize],
+                        if lim.y < 0 { 0 } else { lim.y+1 }
+                    );
             }
         }
 
-        for chunk_idx in GridWindowIterator::from(self.top.range()) {
+        for chunk_idx in GridWindowIterator::from(top_range.clone()) {
             if let Some(chunk) = self.chunks.get_mut(&chunk_idx) {
                 let old_offset = chunk.offset;
                 let old_limit = chunk.limit;
 
-                chunk.limit = chunk.view.range().end;
+                chunk.limit = *chunk.view.area().range().end();
                 chunk.offset = Vector2::new(
                     (0 .. chunk_idx.x as usize).map(|x| col_widths[x]).sum(),
                     (0 .. chunk_idx.y as usize).map(|y| row_heights[y]).sum()
                 );
+/*
                 if old_offset != chunk.offset {
-                    dirty_idx.extend(
-                        GridWindowIterator::from(
-                            Point2::new(std::cmp::min(old_offset.x, chunk.offset.x),
-                                        std::cmp::min(old_offset.y, chunk.offset.y))
-                                .. Point2::new(std::cmp::max(old_offset.x + old_limit.x, chunk.offset.x + chunk.limit.x),
-                                               std::cmp::max(old_offset.y + old_limit.y, chunk.offset.y + chunk.limit.y)))
+                    self.cast.notify(
+                        &IndexArea::Range(
+                            Point2::new(
+                                std::cmp::min(old_offset.x, chunk.offset.x),
+                                std::cmp::min(old_offset.y, chunk.offset.y)
+                            )
+                                ..= Point2::new(
+                                    std::cmp::max(old_offset.x + old_limit.x, chunk.offset.x + chunk.limit.x),
+                                    std::cmp::max(old_offset.y + old_limit.y, chunk.offset.y + chunk.limit.y)
+                                )
+                        )
                     );
                 }
+*/
             }
         }
 
         let old_limit = self.limit;
         self.limit = Point2::new(
-            (0 .. top_range.end.x as usize).map(|x| col_widths[x]).sum(),
-            (0 .. top_range.end.y as usize).map(|y| row_heights[y]).sum()
+            (0 ..= top_range.end().x as usize).map(|x| col_widths[x]).sum::<i16>() - 1,
+            (0 ..= top_range.end().y as usize).map(|y| row_heights[y]).sum::<i16>() - 1,
         );
 
-        // fixme: dirty hack to mitigate the buggy notifications, not efficien
-        dirty_idx.extend(
-            GridWindowIterator::from(
-                Point2::new(0, 0) .. Point2::new(
-                    std::cmp::max(old_limit.x, self.limit.x),
-                    std::cmp::max(old_limit.y, self.limit.y)
-                )
+        self.cast.notify(
+            &IndexArea::Range(
+                Point2::new(0, 0) ..= Point2::new(max(self.limit.x, old_limit.x), max(self.limit.y, old_limit.y))
             )
         );
-
-        self.cast.notify_each(dirty_idx);
     }
 
     /// given an index in the flattened sequence,
     /// which sub-sequence does it belong to?
     fn get_chunk_idx(&self, glob_pos: Point2<i16>) -> Option<Point2<i16>> {
-        for chunk_idx in GridWindowIterator::from(self.top.range()) {
+        for chunk_idx in GridWindowIterator::from(self.top.area().range()) {
             if let Some(chunk) = self.chunks.get(&chunk_idx) {
-                let chunk_range = chunk.view.range();
-                let end = chunk_range.end + chunk.offset;
+                let end = chunk.limit + chunk.offset;
 
-                if glob_pos.x < end.x && glob_pos.y < end.y {
+                if glob_pos.x <= end.x && glob_pos.y <= end.y {
                     return Some(chunk_idx);
                 }
             }
diff --git a/nested/src/grid/mod.rs b/nested/src/grid/mod.rs
index 29ea36d..e44592f 100644
--- a/nested/src/grid/mod.rs
+++ b/nested/src/grid/mod.rs
@@ -1,81 +1,81 @@
+
 use {
     std::{
-        ops::{Range, RangeInclusive}
+        ops::RangeInclusive,
+        cmp::{min, max}
     },
     cgmath::{Point2},
-    crate::{
-        index::{IndexView}
-    }
+    crate::index::{IndexArea, IndexView}
 };
 
-pub mod offset;
-pub mod flatten;
-
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
 pub trait GridView = IndexView<Point2<i16>>;
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
-impl<Item> dyn GridView<Item = Item> {
-    pub fn range(&self) -> Range<Point2<i16>> {
-        if let Some(area) = self.area() {
-            Point2::new(
-                area.iter().map(|p| p.x).min().unwrap_or(0),
-                area.iter().map(|p| p.y).min().unwrap_or(0)
-            ) ..
-                Point2::new(
-                    area.iter().map(|p| p.x+1).max().unwrap_or(0),
-                    area.iter().map(|p| p.y+1).max().unwrap_or(0)
-                )
-        } else {
-            Point2::new(i16::MIN, i16::MIN) .. Point2::new(i16::MAX, i16::MAX)
-        }
-    }
-}
+pub mod offset;
+pub mod flatten;
+pub mod window_iterator;
+
+pub use window_iterator::GridWindowIterator;
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
-pub struct GridWindowIterator {
-    next: Point2<i16>,
-    range: Range<Point2<i16>>
-}
+impl IndexArea<Point2<i16>> {
 
-impl From<Range<Point2<i16>>> for GridWindowIterator {
-    fn from(range: Range<Point2<i16>>) -> Self {
-        GridWindowIterator {
-            next: range.start,
-            range
-        }
-    }
-}
-
-impl From<RangeInclusive<Point2<i16>>> for GridWindowIterator {
-    fn from(range: RangeInclusive<Point2<i16>>) -> Self {
-        GridWindowIterator {
-            next: *range.start(),
-            range: *range.start() .. Point2::new(range.end().x+1, range.end().y+1)
-        }
-    }
-}
-
-impl Iterator for GridWindowIterator {
-    type Item = Point2<i16>;
-
-    fn next(&mut self) -> Option<Point2<i16>> {
-        if self.next.y < self.range.end.y {
-            let next = self.next;
-
-            if self.next.x+1 < self.range.end.x {
-                self.next.x += 1;
-            } else {
-                self.next.x = self.range.start.x;
-                self.next.y += 1;
-            }
-
-            Some(next)
-        } else {
-            None
+    // todo: this is not perfect (e.g. diagonals are inefficient)
+    pub fn iter(&self) -> GridWindowIterator {
+        GridWindowIterator::from(self.range())
+    }
+
+    pub fn range(&self) -> RangeInclusive<Point2<i16>> {
+        match self {
+            IndexArea::Empty => Point2::new(i16::MAX, i16::MAX) ..= Point2::new(i16::MIN, i16::MIN),
+            IndexArea::Full => panic!("range from full grid area"),
+            IndexArea::Set(v) =>
+                Point2::new(
+                    v.iter().map(|p| p.x).min().unwrap_or(0),
+                    v.iter().map(|p| p.y).min().unwrap_or(0)
+                ) ..=
+                Point2::new(
+                    v.iter().map(|p| p.x).max().unwrap_or(0),
+                    v.iter().map(|p| p.y).max().unwrap_or(0)
+                ),
+            IndexArea::Range(r) => r.clone()
+        }
+    }
+
+    pub fn union(self, other: IndexArea<Point2<i16>>) -> IndexArea<Point2<i16>> {
+        match (self, other) {
+            (IndexArea::Empty, a) |
+            (a, IndexArea::Empty) => a,
+
+            (IndexArea::Full, _) |
+            (_, IndexArea::Full) => IndexArea::Full,
+
+            (IndexArea::Set(mut va), IndexArea::Set(mut vb)) => {
+                va.extend(vb.into_iter());
+                IndexArea::Set(va)
+            },
+
+            (IndexArea::Range(r), IndexArea::Set(mut v)) |
+            (IndexArea::Set(mut v), IndexArea::Range(r)) => {
+                v.extend(GridWindowIterator::from(r));
+                IndexArea::Set(v)
+            },
+
+            (IndexArea::Range(ra), IndexArea::Range(rb)) => IndexArea::Range(
+                Point2::new(
+                    min(ra.start().x, rb.start().x),
+                    min(ra.start().y, rb.start().y)
+                )
+                    ..=
+                    Point2::new(
+                        max(ra.end().x, rb.end().x),
+                        max(ra.end().y, rb.end().y)
+                    )
+            )
         }
     }
 }
diff --git a/nested/src/grid/window_iterator.rs b/nested/src/grid/window_iterator.rs
new file mode 100644
index 0000000..b2f587e
--- /dev/null
+++ b/nested/src/grid/window_iterator.rs
@@ -0,0 +1,60 @@
+
+use {
+    std::ops::{Range, RangeInclusive},
+    cgmath::{Point2}
+};
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+pub struct GridWindowIterator {
+    next: Point2<i16>,
+    range: Range<Point2<i16>>
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl From<Range<Point2<i16>>> for GridWindowIterator {
+    fn from(range: Range<Point2<i16>>) -> Self {
+        GridWindowIterator {
+            next: range.start,
+            range
+        }
+    }
+}
+
+impl From<RangeInclusive<Point2<i16>>> for GridWindowIterator {
+    fn from(range: RangeInclusive<Point2<i16>>) -> Self {
+        GridWindowIterator {
+            next: *range.start(),
+            range: *range.start() .. Point2::new(range.end().x+1, range.end().y+1)
+        }
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl Iterator for GridWindowIterator {
+    type Item = Point2<i16>;
+
+    fn next(&mut self) -> Option<Point2<i16>> {
+        if self.next.y < self.range.end.y {
+            if self.next.x < self.range.end.x {
+                let next = self.next;
+
+                if self.next.x+1 < self.range.end.x {
+                    self.next.x += 1;
+                } else {
+                    self.next.x = self.range.start.x;
+                    self.next.y += 1;
+                }
+
+                Some(next)
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
+}
+
diff --git a/nested/src/index/buffer.rs b/nested/src/index/buffer.rs
index f14beaf..43fa9be 100644
--- a/nested/src/index/buffer.rs
+++ b/nested/src/index/buffer.rs
@@ -13,7 +13,7 @@ use {
             View,
             InnerViewPort
         },
-        index::IndexView
+        index::{IndexArea, IndexView}
     }
 };
 
@@ -25,7 +25,7 @@ impl<Key, Item> View for IndexBufferView<Key, Item>
 where Key: Clone + Hash + Eq + Send + Sync + 'static,
       Item: Clone + Send + Sync + 'static
 {
-    type Msg = Key;
+    type Msg = IndexArea<Key>;
 }
 
 impl<Key, Item> IndexView<Key> for IndexBufferView<Key, Item>
@@ -38,12 +38,11 @@ where Key: Clone + Hash + Eq + Send + Sync + 'static,
         self.0.read().unwrap().get(key).cloned()
     }
 
-    fn area(&self) -> Option<Vec<Key>> {
-        Some(self.0.read().unwrap().keys().cloned().collect())
+    fn area(&self) -> IndexArea<Key> {
+        IndexArea::Set(self.0.read().unwrap().keys().cloned().collect())
     }
 }
 
-
 pub struct IndexBuffer<Key, Item>
 where Key: Clone + Hash + Eq + Send + Sync + 'static,
       Item: Clone + Send + Sync + 'static
@@ -68,7 +67,7 @@ where Key: Clone + Hash + Eq + Send + Sync + 'static,
 
     pub fn insert(&mut self, key: Key, item: Item) {
         self.data.write().unwrap().insert(key.clone(), item);
-        self.cast.notify(&key);
+        self.cast.notify(&IndexArea::Set(vec![ key ]));
     }
 
     pub fn insert_iter<T>(&mut self, iter: T)
@@ -80,7 +79,7 @@ where Key: Clone + Hash + Eq + Send + Sync + 'static,
 
     pub fn remove(&mut self, key: Key) {
         self.data.write().unwrap().remove(&key);
-        self.cast.notify(&key);        
+        self.cast.notify(&IndexArea::Set(vec![ key ]));
     }
 }
 
diff --git a/nested/src/index/map_item.rs b/nested/src/index/map_item.rs
index f12f2c6..d9c5711 100644
--- a/nested/src/index/map_item.rs
+++ b/nested/src/index/map_item.rs
@@ -14,7 +14,7 @@ pub use {
             InnerViewPort,
             OuterViewPort
         },
-        index::{IndexView}
+        index::{IndexArea, IndexView}
     }
 };
 
@@ -76,7 +76,7 @@ where Key: Clone + Send + Sync,
       SrcView: IndexView<Key> + ?Sized,
       F: Fn(&Key, &SrcView::Item) -> DstItem + Send + Sync
 {
-    type Msg = Key;
+    type Msg = IndexArea<Key>;
 }
 
 impl<Key, DstItem, SrcView, F> IndexView<Key> for MapIndexItem<Key, DstItem, SrcView, F>
@@ -90,7 +90,7 @@ where Key: Clone + Send + Sync,
         self.src_view.get(key).as_ref().map(|item| (self.f)(key, item))
     }
 
-    fn area(&self) -> Option<Vec<Key>> {
+    fn area(&self) -> IndexArea<Key> {
         self.src_view.area()
     }
 }
@@ -102,15 +102,15 @@ where Key: Clone + Send + Sync,
 {
     fn reset(&mut self, view: Option<Arc<SrcView>>) {
         let old_area = self.area();
-        self.src_view = view;
-        let new_area = self.area();
 
-        if let Some(area) = old_area { self.cast.notify_each(area); }
-        if let Some(area) = new_area { self.cast.notify_each(area); }
+        self.src_view = view;
+
+        self.cast.notify(&old_area);
+        self.cast.notify(&self.src_view.area())
     }
 
-    fn notify(&mut self, msg: &Key) {
-        self.cast.notify(msg);
+    fn notify(&mut self, area: &IndexArea<Key>) {
+        self.cast.notify(area);
     }
 }
 
diff --git a/nested/src/index/map_key.rs b/nested/src/index/map_key.rs
index 4635f4c..7ba392d 100644
--- a/nested/src/index/map_key.rs
+++ b/nested/src/index/map_key.rs
@@ -14,7 +14,7 @@ pub use {
             InnerViewPort,
             OuterViewPort
         },
-        index::{IndexView},
+        index::{IndexArea, IndexView},
         grid::{GridView}
     }
 };
@@ -106,7 +106,7 @@ where DstKey: Clone + Send + Sync,
       F1: Fn(&SrcKey) -> DstKey + Send + Sync,
       F2: Fn(&DstKey) -> Option<SrcKey> + Send + Sync,
 {
-    type Msg = DstKey;
+    type Msg = IndexArea<DstKey>;
 }
 
 impl<DstKey, SrcKey, SrcView, F1, F2> IndexView<DstKey> for MapIndexKey<DstKey, SrcKey, SrcView, F1, F2>
@@ -122,8 +122,8 @@ where DstKey: Clone + Send + Sync,
         self.src_view.get(&(self.f2)(key)?)
     }
 
-    fn area(&self) -> Option<Vec<DstKey>> {
-        Some(self.src_view.area()?.iter().map(&self.f1).collect())
+    fn area(&self) -> IndexArea<DstKey> {
+        self.src_view.area().map(&self.f1)
     }
 }
 
@@ -137,14 +137,12 @@ where DstKey: Clone + Send + Sync,
     fn reset(&mut self, view: Option<Arc<SrcView>>) {
         let old_area = self.area();
         self.src_view = view;
-        let new_area = self.area();
-
-        if let Some(area) = old_area { self.cast.notify_each(area); }
-        if let Some(area) = new_area { self.cast.notify_each(area); }
+        self.cast.notify(&old_area);
+        self.cast.notify(&self.area());
     }
 
-    fn notify(&mut self, msg: &SrcKey) {
-        self.cast.notify(&(self.f1)(msg));
+    fn notify(&mut self, msg: &IndexArea<SrcKey>) {
+        self.cast.notify(&msg.map(&self.f1));
     }
 }
 
diff --git a/nested/src/index/mod.rs b/nested/src/index/mod.rs
index f639ef7..ab656d0 100644
--- a/nested/src/index/mod.rs
+++ b/nested/src/index/mod.rs
@@ -6,7 +6,7 @@ pub mod buffer;
 use {
     std::{
         sync::Arc,
-        ops::Deref,
+        ops::{Deref, RangeInclusive},
     },
     std::sync::RwLock,
     crate::core::View
@@ -14,15 +14,34 @@ use {
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
-pub trait IndexView<Key> : View<Msg = Key>
+#[derive(Clone)]
+pub enum IndexArea<Key> {
+    Empty,
+    Full,
+    Set(Vec<Key>),
+    Range(RangeInclusive<Key>),
+    //Procedural(Arc<dyn Fn() -> Box<dyn Iterator<Item = Key>>>)
+}
+
+impl<Key> IndexArea<Key> {
+    pub fn map<T>(&self, f: impl Fn(&Key) -> T) -> IndexArea<T> {
+        match self {
+            IndexArea::Empty => IndexArea::Empty,
+            IndexArea::Full => IndexArea::Full,
+            IndexArea::Set(v) => IndexArea::Set(v.iter().map(&f).collect()),
+            IndexArea::Range(r) => IndexArea::Range(f(&r.start()) ..= f(&r.end()))
+        }
+    }
+}
+
+pub trait IndexView<Key> : View<Msg = IndexArea<Key>>
 where Key: Send + Sync {
     type Item;
 
     fn get(&self, key: &Key) -> Option<Self::Item>;
 
-    // todo: AreaIterator enum to switch between Allocated and Procedural area
-    fn area(&self) -> Option<Vec<Key>> {
-        None
+    fn area(&self) -> IndexArea<Key> {
+        IndexArea::Full
     }
 }
 
@@ -38,7 +57,7 @@ where Key: Send + Sync,
         self.read().unwrap().get(key)
     }
 
-    fn area(&self) -> Option<Vec<Key>> {
+    fn area(&self) -> IndexArea<Key> {
         self.read().unwrap().area()
     }
 }
@@ -53,7 +72,7 @@ where Key: Send + Sync,
         self.deref().get(key)
     }
 
-    fn area(&self) -> Option<Vec<Key>> {
+    fn area(&self) -> IndexArea<Key> {
         self.deref().area()
     }
 }
@@ -68,17 +87,17 @@ where Key: Send + Sync,
         self.as_ref()?.get(key)
     }
 
-    fn area(&self) -> Option<Vec<Key>> {
+    fn area(&self) -> IndexArea<Key> {
         if let Some(v) = self.as_ref() {
             v.area()
         } else {
-            Some(Vec::new())
+            IndexArea::Empty
         }
     }
 }
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
-
+/*
 pub trait ImplIndexView : Send + Sync {
     type Key : Send + Sync;
     type Value;
@@ -104,4 +123,4 @@ impl<V: ImplIndexView> IndexView<V::Key> for V {
         (self as &V).area()
     }
 }
-
+*/
diff --git a/nested/src/leveled_term_view.rs b/nested/src/leveled_term_view.rs
deleted file mode 100644
index 919c6f8..0000000
--- a/nested/src/leveled_term_view.rs
+++ /dev/null
@@ -1,94 +0,0 @@
-use {
-    std::{
-        sync::{Arc}
-    },
-    std::sync::RwLock,
-    cgmath::Point2,
-    crate::{
-        core::{ViewPort, Observer, ObserverExt, ObserverBroadcast, InnerViewPort, OuterViewPort},
-        index::{ImplIndexView},
-        terminal::{TerminalAtom, TerminalView, TerminalStyle},
-        projection::{ProjectionHelper}
-    }
-};
-
-//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
-
-pub struct LeveledTermView {
-    src: Arc<RwLock<dyn TerminalView>>,
-    level: usize,
-
-    cast: Arc<RwLock<ObserverBroadcast<dyn TerminalView>>>,
-    proj_helper: ProjectionHelper<(), Self>
-}
-
-impl LeveledTermView {
-    pub fn new(
-        src: OuterViewPort<dyn TerminalView>
-    ) -> (Arc<RwLock<Self>>, OuterViewPort<dyn TerminalView>) {
-        let port = ViewPort::new();
-        let v = Self::with_port(src, port.inner());
-        (v, port.into_outer())
-    }
-
-    pub fn with_port(
-        src_port: OuterViewPort<dyn TerminalView>,
-        dst_port: InnerViewPort<dyn TerminalView>
-    ) -> Arc<RwLock<Self>> {
-        let mut proj_helper = ProjectionHelper::new(dst_port.0.update_hooks.clone());
-
-        let v = Arc::new(RwLock::new(
-            LeveledTermView {
-                src: proj_helper.new_index_arg(
-                    (),
-                    src_port,
-                    |p: &mut Self, pos: &Point2<i16>| {
-                        p.cast.notify(pos);
-                    }),
-                level: 0,
-                cast: dst_port.get_broadcast(),
-                proj_helper
-            }
-        ));
-
-        v.write().unwrap().proj_helper.set_proj(&v);
-        dst_port.set_view(Some(v.clone()));
-
-        v
-    }
-
-    pub fn set_level(&mut self, l: usize) {
-        if self.level != l {
-            self.level = l;
-
-            // update complete area
-            if let Some(a) = self.src.area() {
-                self.cast.notify_each(a);
-            }
-        }
-    }
-}
-
-impl ImplIndexView for LeveledTermView {
-    type Key = Point2<i16>;
-    type Value = TerminalAtom;
-
-    fn get(&self, pos: &Point2<i16>) -> Option<TerminalAtom> {
-        self.src.get(pos).map(
-            |a| a.add_style_front(
-                if self.level > 1 {
-                    TerminalStyle::bold(true)
-                        .add(TerminalStyle::bg_color((0, 0, 0)))
-                } else if self.level > 0 {
-                    TerminalStyle::bg_color((40, 40, 40))
-                } else {
-                    TerminalStyle::bold(false)
-                })
-        )
-    }
-
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        self.src.area()
-    }
-}
-
diff --git a/nested/src/lib.rs b/nested/src/lib.rs
index 7967491..611d921 100644
--- a/nested/src/lib.rs
+++ b/nested/src/lib.rs
@@ -15,7 +15,6 @@ pub mod list;
 pub mod tree_nav;
 
 pub mod string_editor;
-pub mod leveled_term_view;
 
 pub mod bimap;
 
diff --git a/nested/src/list/editor.rs b/nested/src/list/editor.rs
index e3a48cd..e80d43a 100644
--- a/nested/src/list/editor.rs
+++ b/nested/src/list/editor.rs
@@ -3,22 +3,9 @@ use {
     termion::event::{Event, Key},
     crate::{
         core::{
-            View,
             ViewPort,
             OuterViewPort,
-            InnerViewPort,
-            ObserverBroadcast,
-            Observer,
-            ObserverExt,
-            context::{
-                ReprTree,
-                Object,
-                MorphismType,
-                MorphismMode,
-                Context
-            }
         },
-        projection::ProjectionHelper,
         singleton::{SingletonView, SingletonBuffer},
         sequence::{SequenceView},
         vec::{VecBuffer},
@@ -30,7 +17,6 @@ use {
             TerminalEditorResult,
             make_label
         },
-        leveled_term_view::LeveledTermView,
         list::{SExprView, ListDecoration, ListCursor, ListCursorMode, editor_view::{ListEditorView, ListEditorViewSegment}},
         tree_nav::{TreeCursor, TreeNav, TreeNavResult, TerminalTreeEditor}
     }
@@ -61,6 +47,7 @@ where ItemEditor: TerminalEditor + ?Sized + Send + Sync + 'static,
 
     style: ListEditorStyle,
     level: usize,
+    cur_dist: Arc<RwLock<usize>>,
 }
 
 impl<ItemEditor, FnMakeItemEditor> TreeNav for ListEditor<ItemEditor, FnMakeItemEditor>
@@ -326,6 +313,7 @@ where ItemEditor: TerminalTreeEditor + ?Sized + Send + Sync + 'static,
                                 tree_addr: vec![]
                             }
                         );
+                        *self.cur_dist.write().unwrap() += 1;
                     }
                 }
                 TreeNavResult::Continue
@@ -586,7 +574,7 @@ where ItemEditor: TerminalTreeEditor + ?Sized + Send + Sync + 'static,
 }
 
 impl<ItemEditor, FnMakeItemEditor> ListEditor<ItemEditor, FnMakeItemEditor>
-where ItemEditor: TerminalEditor + ?Sized + Send + Sync + 'static,
+where ItemEditor: TerminalTreeEditor + ?Sized + Send + Sync + 'static,
       FnMakeItemEditor: Fn() -> Arc<RwLock<ItemEditor>>
 {
     pub fn get_seg_seq_view(&self) -> OuterViewPort<dyn SequenceView<Item = OuterViewPort<dyn TerminalView>>> {
@@ -596,32 +584,39 @@ where ItemEditor: TerminalEditor + ?Sized + Send + Sync + 'static,
             self.data_port.outer().to_sequence().map(|ed| ed.read().unwrap().get_term_view()),
             segment_view_port.inner()
         );
+
         segment_view_port.into_outer()
             .map(
-                |segment| match segment {
+                move |segment| {
+                    let cursor_col = (90, 60, 200);
+                match segment {
                     ListEditorViewSegment::InsertCursor =>
                         make_label("|")
                         .map_item(
-                            |_pt, atom|
-                            atom.add_style_back(TerminalStyle::fg_color((90,60,200)))
-                                //.add_style_back(TerminalStyle::bg_color((0,0,0)))
+                            move |_pt, atom|
+                            atom.add_style_back(TerminalStyle::fg_color(cursor_col))
                                 .add_style_back(TerminalStyle::bold(true))
                         ),
                     ListEditorViewSegment::Select(sub_view) =>
                         sub_view.map_item(
-                            |_pt, atom|
-                            atom.add_style_front(TerminalStyle::bg_color((90,60,200)))
+                            move |_pt, atom| {
+                                let old_col = atom.style.bg_color.unwrap_or(cursor_col);
+                                atom.add_style_front(TerminalStyle::bg_color(((old_col.0 as f32 * 0.4) as u8, (old_col.1 as f32 * 0.4) as u8, (old_col.2 as f32 * 0.4) as u8)))
+                            }
                         ),
                     ListEditorViewSegment::Modify(sub_view) => {
                         sub_view.clone().map_item(
-                            |_pt, atom|
-                            atom.add_style_back(TerminalStyle::bg_color((22,15,50)))
+                            move |_pt, atom| {
+                                let old_col = atom.style.bg_color.unwrap_or(cursor_col);
+                                atom.add_style_front(TerminalStyle::bg_color(((old_col.0 as f32 * 0.4) as u8, (old_col.1 as f32 * 0.4) as u8, (old_col.2 as f32 * 0.4) as u8)))
+                            }
                                 //.add_style_back(TerminalStyle::bold(true))
                         )
                     },
                     ListEditorViewSegment::View(sub_view) =>
                         sub_view.clone()
                 }
+                }
             )
     }
 
@@ -644,6 +639,7 @@ where ItemEditor: TerminalEditor + ?Sized + Send + Sync + 'static,
         self.get_seg_seq_view()
             .decorate("\"", "\"", "", 1)
             .to_grid_horizontal()
+
             .flatten()
     }
 
@@ -681,7 +677,8 @@ where ItemEditor: TerminalEditor + ?Sized + Send + Sync + 'static,
 
             style,
             make_item_editor,
-            level: 0
+            level: 0,
+            cur_dist: Arc::new(RwLock::new(0))
         };
         le.set_style(style);
         le
diff --git a/nested/src/list/sexpr.rs b/nested/src/list/sexpr.rs
index ec4f09f..7aa37d0 100644
--- a/nested/src/list/sexpr.rs
+++ b/nested/src/list/sexpr.rs
@@ -3,6 +3,7 @@ use {
         core::{InnerViewPort, Observer, ObserverBroadcast, OuterViewPort, View, ViewPort},
         projection::ProjectionHelper,
         sequence::SequenceView,
+        index::{IndexArea},
         terminal::{make_label, TerminalStyle, TerminalView},
     },
     cgmath::Point2,
@@ -141,19 +142,16 @@ pub struct VerticalSexprDecorator {
 }
 
 impl View for VerticalSexprDecorator {
-    type Msg = Point2<i16>;
+    type Msg = IndexArea<Point2<i16>>;
 }
 
 impl IndexView<Point2<i16>> for VerticalSexprDecorator {
     type Item = OuterViewPort<dyn TerminalView>;
 
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        let mut area = (0..self.items.len()?)
-            .map(|i| Point2::new(1 as i16, i as i16))
-            .collect::<Vec<_>>();
-        area.push(Point2::new(0, 0));
-        area.push(Point2::new(2, self.items.len()? as i16 - 1));
-        Some(area)
+    fn area(&self) -> IndexArea<Point2<i16>> {
+        IndexArea::Range(
+            Point2::new(0, 0) ..= Point2::new(2, std::cmp::max(self.items.len().unwrap() as i16 - 1, 0))
+        )
     }
 
     fn get(&self, pt: &Point2<i16>) -> Option<Self::Item> {
@@ -218,9 +216,11 @@ impl VerticalSexprDecorator {
             opening_port: make_label(opening),
             closing_port: make_label(closing),
             items: proj_helper.new_sequence_arg((), items_port, |s: &mut Self, item_idx| {
-                s.cast.notify(&Point2::new(1, *item_idx as i16));
-                s.cast.notify(&Point2::new(2, *item_idx as i16 - 1));
-                s.cast.notify(&Point2::new(2, *item_idx as i16));
+                s.cast.notify(
+                    &IndexArea::Range(
+                        Point2::new(0, *item_idx as i16) ..= Point2::new(2, *item_idx as i16)
+                    )
+                );
             }),
             list_style: TerminalStyle::fg_color(match level {
                 0 => (200, 120, 10),
diff --git a/nested/src/projection.rs b/nested/src/projection.rs
index 7ab80bd..ffd6995 100644
--- a/nested/src/projection.rs
+++ b/nested/src/projection.rs
@@ -16,12 +16,13 @@ use {
             channel::{
                 ChannelSender, ChannelReceiver,
                 ChannelData,
-                set_channel
+                set_channel,
+                queue_channel
             }
         },
         singleton::{SingletonView},
         sequence::{SequenceView},
-        index::{IndexView}
+        index::{IndexArea, IndexView}
     }
 };
 
@@ -75,13 +76,13 @@ where ArgKey: Clone + Hash + Eq,
         port.get_view_arc()
     }
 
-    pub fn new_index_arg<Key: Hash + Eq + Clone + Send + Sync + std::fmt::Debug + 'static, Item: 'static>(
+    pub fn new_index_arg<Key: Clone + Send + Sync + 'static, Item: 'static>(
         &mut self,
         arg_key: ArgKey,
         port: OuterViewPort<dyn IndexView<Key, Item = Item>>,
-        notify: impl Fn(&mut P, &Key) + Send + Sync + 'static
+        notify: impl Fn(&mut P, &IndexArea<Key>) + Send + Sync + 'static
     ) -> Arc<RwLock<Option<Arc<dyn IndexView<Key, Item = Item>>>>> {
-        port.add_observer(self.new_arg(arg_key, Arc::new(port.0.clone()), notify, set_channel()));
+        port.add_observer(self.new_arg(arg_key, Arc::new(port.0.clone()), notify, queue_channel()));
         port.get_view_arc()
     }
 
@@ -96,7 +97,7 @@ where ArgKey: Clone + Hash + Eq,
         (tx, rx): (ChannelSender<D>, ChannelReceiver<D>)
     )
         -> Arc<RwLock<ProjectionArg<P, V, D>>>
-    where V::Msg: Send + Sync + std::fmt::Debug,
+    where V::Msg: Send + Sync,
           D::IntoIter: Send + Sync + 'static
     {
         self.remove_arg(&arg_key);
@@ -151,8 +152,7 @@ impl<P, V, D> UpdateTask for ProjectionArg<P, V, D>
 where P: Send + Sync + 'static,
       V: View + ?Sized,
       D: ChannelData<Item = V::Msg>,
-      D::IntoIter: Send + Sync,
-V::Msg: std::fmt::Debug
+      D::IntoIter: Send + Sync
 {
     fn update(&self) {
         if let Some(p) = self.proj.read().unwrap().upgrade() {
@@ -175,8 +175,7 @@ impl<P, V, D> UpdateTask for RwLock<ProjectionArg<P, V, D>>
 where P: Send + Sync + 'static,
       V: View + ?Sized,
       D: ChannelData<Item = V::Msg>,
-      D::IntoIter: Send + Sync,
-V::Msg: std::fmt::Debug
+      D::IntoIter: Send + Sync
 {
     fn update(&self) {
         self.read().unwrap().update();
@@ -225,19 +224,18 @@ where P: Send + Sync + 'static,
 impl<P, Key, Item, D> Observer<dyn IndexView<Key, Item = Item>> for ProjectionArg<P, dyn IndexView<Key, Item = Item>, D>
 where P: Send + Sync + 'static,
       Key: Clone + Send + Sync,
-      D: ChannelData<Item = Key>,
+      D: ChannelData<Item = IndexArea<Key>>,
       D::IntoIter: Send + Sync
 {
     fn reset(&mut self, new_src: Option<Arc<dyn IndexView<Key, Item = Item>>>) {
         let old_area = self.src.area();
         self.src = new_src;
-        let new_area = self.src.area();
 
-        if let Some(area) = old_area { self.notify_each(area); }
-        if let Some(area) = new_area { self.notify_each(area); }
+        self.notify(&old_area);
+        self.notify(&self.src.area())
     }
 
-    fn notify(&mut self, msg: &Key) {
+    fn notify(&mut self, msg: &IndexArea<Key>) {
         self.tx.send(msg.clone());
     }
 }
diff --git a/nested/src/sequence/seq2idx.rs b/nested/src/sequence/seq2idx.rs
index 17df9e7..530c33e 100644
--- a/nested/src/sequence/seq2idx.rs
+++ b/nested/src/sequence/seq2idx.rs
@@ -5,11 +5,11 @@ use {
     std::sync::RwLock,
     crate::{
         core::{
-            View, Observer, ObserverExt, ObserverBroadcast,
+            View, Observer, ObserverBroadcast,
             ViewPort, InnerViewPort, OuterViewPort
         },
         sequence::SequenceView,
-        index::IndexView,
+        index::{IndexArea, IndexView},
         grid::GridView
     }
 };
@@ -56,7 +56,7 @@ impl<Item: 'static> OuterViewPort<dyn SequenceView<Item = Item>> {
 
 impl<SrcView> View for Sequence2Index<SrcView>
 where SrcView: SequenceView + ?Sized + 'static {
-    type Msg = usize;
+    type Msg = IndexArea<usize>;
 }
 
 impl<SrcView> IndexView<usize> for Sequence2Index<SrcView>
@@ -67,8 +67,16 @@ where SrcView: SequenceView + ?Sized + 'static {
         self.src_view.get(key)
     }
 
-    fn area(&self) -> Option<Vec<usize>> {
-        Some((0 .. self.src_view.len()?).collect())
+    fn area(&self) -> IndexArea<usize> {
+        if let Some(len) = self.src_view.len() {
+            if len > 0 {
+                IndexArea::Range(0 ..= len-1)
+            } else {
+                IndexArea::Empty
+            }
+        } else {
+            IndexArea::Full
+        }
     }
 }
 
@@ -77,14 +85,13 @@ where SrcView: SequenceView + ?Sized + 'static {
     fn reset(&mut self, view: Option<Arc<SrcView>>) {
         let old_area = self.area();
         self.src_view = view;
-        let new_area = self.area();
 
-        if let Some(area) = old_area { self.cast.notify_each(area); }
-        if let Some(area) = new_area { self.cast.notify_each(area); }
+        self.cast.notify(&old_area);
+        self.cast.notify(&self.area());
     }
 
-    fn notify(&mut self, msg: &usize) {
-        self.cast.notify(msg);
+    fn notify(&mut self, idx: &usize) {
+        self.cast.notify(&IndexArea::Set(vec![ *idx ]));
     }
 }
 
diff --git a/nested/src/singleton/map.rs b/nested/src/singleton/map.rs
index e97802a..1f88a45 100644
--- a/nested/src/singleton/map.rs
+++ b/nested/src/singleton/map.rs
@@ -4,7 +4,7 @@ use {
     crate::{
         singleton::{SingletonView},
         core::{
-            Observer, ObserverExt, ObserverBroadcast,
+            Observer, ObserverBroadcast,
             View, ViewPort, OuterViewPort
         }
     }
diff --git a/nested/src/singleton/to_index.rs b/nested/src/singleton/to_index.rs
index 28372af..3cf4991 100644
--- a/nested/src/singleton/to_index.rs
+++ b/nested/src/singleton/to_index.rs
@@ -3,10 +3,10 @@ use {
     std::sync::RwLock,
     crate::{
         singleton::{SingletonView},
-        index::{IndexView},
+        index::{IndexArea, IndexView},
         grid::{GridView},
         core::{
-            Observer, ObserverExt, ObserverBroadcast,
+            Observer, ObserverBroadcast,
             View, ViewPort, OuterViewPort
         }
     }
@@ -52,7 +52,7 @@ where SrcView: SingletonView + ?Sized
 impl<SrcView> View for Singleton2Index<SrcView>
 where SrcView: SingletonView + ?Sized
 {
-    type Msg = ();
+    type Msg = IndexArea<()>;
 }
 
 impl<SrcView> IndexView<()> for Singleton2Index<SrcView>
@@ -60,9 +60,10 @@ where SrcView: SingletonView + ?Sized
 {
     type Item = SrcView::Item;
 
-    fn area(&self) -> Option<Vec<()>> {
-        Some(vec![()])
+    fn area(&self) -> IndexArea<()> {
+        IndexArea::Full
     }
+
     fn get(&self, _msg: &()) -> Option<Self::Item> {
         Some(self.src_view.as_ref().unwrap().get())
     }
@@ -75,11 +76,11 @@ where SrcView: SingletonView + ?Sized
 {
     fn reset(&mut self, view: Option<Arc<SrcView>>) {
         self.src_view = view;
-        self.cast.notify(&());
+        self.cast.notify(&IndexArea::Full);
     }
 
-    fn notify(&mut self, msg: &()) {
-        self.cast.notify(msg);
+    fn notify(&mut self, _: &()) {
+        self.cast.notify(&IndexArea::Full);
     }
 }
 
diff --git a/nested/src/string_editor.rs b/nested/src/string_editor.rs
index 4eae28e..8a3bcb1 100644
--- a/nested/src/string_editor.rs
+++ b/nested/src/string_editor.rs
@@ -6,7 +6,6 @@ use {
         core::{ViewPort, OuterViewPort},
         singleton::{SingletonView, SingletonBuffer},
         sequence::{SequenceView},
-        vec::VecBuffer,
         terminal::{TerminalView, TerminalStyle, TerminalEvent, TerminalEditor, TerminalEditorResult},
         list::{ListEditor, sexpr::ListDecoration},
         tree_nav::{TreeNav, TreeNavResult, TreeCursor}
diff --git a/nested/src/terminal/compositor.rs b/nested/src/terminal/compositor.rs
index 6c92f0f..ad4c2c6 100644
--- a/nested/src/terminal/compositor.rs
+++ b/nested/src/terminal/compositor.rs
@@ -5,8 +5,8 @@ use {
     std::sync::RwLock,
     cgmath::Point2,
     crate::{
-        core::{InnerViewPort, OuterViewPort, Observer, ObserverBroadcast},
-        index::{ImplIndexView},
+        core::{InnerViewPort, OuterViewPort, View, Observer, ObserverBroadcast},
+        index::{IndexArea, IndexView},
         terminal::{TerminalAtom, TerminalView},
         projection::ProjectionHelper
     }
@@ -46,8 +46,8 @@ impl TerminalCompositor {
             self.proj_helper.new_index_arg(
                 idx,
                 v,
-                |s: &mut Self, pos| {
-                    s.cast.notify(pos);
+                |s: &mut Self, area| {
+                    s.cast.notify(area);
                 }
             )
         );
@@ -56,9 +56,12 @@ impl TerminalCompositor {
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
-impl ImplIndexView for TerminalCompositor {
-    type Key = Point2<i16>;
-    type Value = TerminalAtom;
+impl View for TerminalCompositor {
+    type Msg = IndexArea<Point2<i16>>;
+}
+
+impl IndexView<Point2<i16>> for TerminalCompositor {
+    type Item = TerminalAtom;
 
     fn get(&self, pos: &Point2<i16>) -> Option<TerminalAtom> {
         let mut atom = None;
@@ -74,21 +77,11 @@ impl ImplIndexView for TerminalCompositor {
         atom
     }
 
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        let mut area = Some(Vec::new());
+    fn area(&self) -> IndexArea<Point2<i16>> {
+        let mut area = IndexArea::Empty;
 
         for layer in self.layers.iter() {
-            if let (
-                Some(mut new_area),
-                Some(area)
-            ) = (
-                layer.area(),
-                area.as_mut()
-            ) {
-                area.append(&mut new_area);
-            } else {
-                area = None;
-            }
+            area = area.union(layer.area());
         }
 
         area
diff --git a/nested/src/terminal/terminal.rs b/nested/src/terminal/terminal.rs
index b34bf1c..d143586 100644
--- a/nested/src/terminal/terminal.rs
+++ b/nested/src/terminal/terminal.rs
@@ -27,6 +27,7 @@ use {
                 set_channel
             }
         },
+        index::{IndexArea},
         grid::{GridWindowIterator}
     },
     super::{
@@ -119,24 +120,40 @@ struct TermOutObserver {
     writer: Arc<TermOutWriter>
 }
 
+impl TermOutObserver {
+    fn send_area(&mut self, area: IndexArea<Point2<i16>>) {
+        match area {
+            IndexArea::Empty => {},
+            IndexArea::Full => {
+                let (w, h) = termion::terminal_size().unwrap();
+                for pos in GridWindowIterator::from(Point2::new(0, 0) .. Point2::new(w as i16, h as i16)) {
+                    self.dirty_pos_tx.send(pos);
+                }
+            }
+            IndexArea::Range(r) => {
+                for pos in GridWindowIterator::from(r) {
+                    self.dirty_pos_tx.send(pos);
+                }
+            }
+            IndexArea::Set(v) => {
+                for pos in v {
+                    self.dirty_pos_tx.send(pos);
+                }
+            }
+        }        
+    }
+}
+
 impl Observer<dyn TerminalView> for TermOutObserver {
     fn reset(&mut self, view: Option<Arc<dyn TerminalView>>) {
         self.writer.reset();
-
-        let (w, h) = termion::terminal_size().unwrap();
         if let Some(view) = view {
-            for pos in view.area().unwrap_or(
-                GridWindowIterator::from(
-                    Point2::new(0, 0) .. Point2::new(w as i16, h as i16)
-                ).collect()
-            ) {
-                self.dirty_pos_tx.send(pos);
-            }
+            self.send_area(view.area());
         }
     }
 
-    fn notify(&mut self, pos: &Point2<i16>) {
-        self.dirty_pos_tx.send(*pos);
+    fn notify(&mut self, area: &IndexArea<Point2<i16>>) {
+        self.send_area(area.clone());
     }
 }
 
@@ -166,10 +183,24 @@ impl TermOutWriter {
 
         // draw atoms until view port is destroyed
         while let Some(dirty_pos) = self.dirty_pos_rx.recv().await {
+            let (w, h) = termion::terminal_size().unwrap();
+
             if let Some(view) = self.view.read().unwrap().as_ref() {
                 let mut out = self.out.write().unwrap();
 
-                for pos in dirty_pos.into_iter().filter(|p| p.x >= 0 && p.y >= 0) {
+                let d = dirty_pos.into_iter().filter(|p| p.x >= 0 && p.y >= 0 && p.x < w as i16 && p.y < w as i16);//.collect::<Vec<_>>();
+                /*
+                d.sort_by(|a,b| {
+                    if a.y < b.y {
+                        std::cmp::Ordering::Less
+                    } else if a.y == b.y {
+                        a.x.cmp(&b.x)
+                    } else {
+                        std::cmp::Ordering::Greater
+                    }
+                });
+*/
+                for pos in d {
                     if pos != cur_pos {
                         write!(out, "{}", termion::cursor::Goto(pos.x as u16 + 1, pos.y as u16 + 1))?;
                     }
diff --git a/rust-toolchain b/rust-toolchain
index 5841773..ea2cce1 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -5,5 +5,5 @@
 # to the user in the error, instead of "error: invalid channel name '[toolchain]'".
 
 [toolchain]
-channel = "nightly-2021-09-29"
+channel = "nightly-2021-10-26"
 components = ["rust-src", "rustc-dev", "llvm-tools-preview"]
diff --git a/shell/src/ascii_box.rs b/shell/src/ascii_box.rs
index 11b20c4..83f014e 100644
--- a/shell/src/ascii_box.rs
+++ b/shell/src/ascii_box.rs
@@ -13,7 +13,7 @@ use{
             ObserverBroadcast,
             context::{ReprTree, Object, MorphismType, MorphismMode, Context},
             port::{UpdateTask}},
-        index::{IndexView},
+        index::{IndexArea, IndexView},
         grid::{GridWindowIterator},
         terminal::{
             Terminal,
@@ -57,14 +57,19 @@ impl AsciiBox {
         if self.extent != new_extent {
             let old_extent = self.extent;
             self.extent = new_extent;
-            self.notify_each(GridWindowIterator::from(Point2::new(0, 0) .. Point2::new(2+std::cmp::max(old_extent.x, new_extent.x), 2+std::cmp::max(old_extent.y, new_extent.y))));
+            self.cast.notify(
+                &IndexArea::Range(
+                    Point2::new(0, 0) ..=
+                        Point2::new(
+                            1+std::cmp::max(old_extent.x, new_extent.x),
+                            1+std::cmp::max(old_extent.y, new_extent.y))));
         }
     }
 
     pub fn fit_content(&mut self) {
         if let Some(c) = self.content.as_ref() {
-            let p = c.range().end;
-            self.resize(Vector2::new(p.x, p.y));
+            let p = *c.area().range().end();
+            self.resize(Vector2::new(p.x+1, p.y+1));
         } else {
             self.resize(Vector2::new(0, 0));
         }
@@ -74,17 +79,17 @@ impl AsciiBox {
 impl Observer<dyn TerminalView> for AsciiBox {
     fn reset(&mut self, new_content: Option<Arc<dyn TerminalView>>) {
         self.content = new_content;
-        self.notify_each(GridWindowIterator::from(Point2::new(0, 0) .. Point2::new(self.extent.x+2, self.extent.y+2)));
+        self.fit_content();
     }
 
-    fn notify(&mut self, pt: &Point2<i16>) {
-        self.cast.notify(&(pt + Vector2::new(1, 1)));
+    fn notify(&mut self, area: &IndexArea<Point2<i16>>) {
+        self.cast.notify(&area.map(|pt| pt + Vector2::new(1, 1)));
         self.fit_content();
     }
 }
 
 impl View for AsciiBox {
-    type Msg = Point2<i16>;
+    type Msg = IndexArea<Point2<i16>>;
 }
 
 impl IndexView<Point2<i16>> for AsciiBox {
@@ -114,19 +119,19 @@ impl IndexView<Point2<i16>> for AsciiBox {
                 None
             }
         } else if
+            pt.x > 0 &&
+            pt.y > 0 &&
             pt.x < self.extent.x+1 &&
             pt.y < self.extent.y+1
         {
-            self.content.get(&(pt - Vector2::new(1, 1)))
+            Some(self.content.get(&(pt - Vector2::new(1, 1))).unwrap_or(TerminalAtom::from(' ')))
         } else {
             None
         }
     }
 
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        Some(GridWindowIterator::from(
-            Point2::new(0, 0) .. Point2::new(self.extent.x+2, self.extent.y+2)
-        ).collect())
+    fn area(&self) -> IndexArea<Point2<i16>> {
+        IndexArea::Range(Point2::new(0, 0) ..= Point2::new(1,1)+self.extent)
     }
-
 }
+
diff --git a/shell/src/box.rs b/shell/src/box.rs
deleted file mode 100644
index 5d895f4..0000000
--- a/shell/src/box.rs
+++ /dev/null
@@ -1,131 +0,0 @@
-
-use{
-    std::sync::{Arc, RwLock},
-    cgmath::{Point2, Vector2},
-    nested::{
-        core::{
-            View,
-            ViewPort,
-            InnerViewPort,
-            OuterViewPort,
-            Observer,
-            ObserverExt,
-            ObserverBroadcast,
-            context::{ReprTree, Object, MorphismType, MorphismMode, Context},
-            port::{UpdateTask}},
-        index::{IndexView},
-        grid::{GridWindowIterator},
-        terminal::{
-            Terminal,
-            TerminalStyle,
-            TerminalAtom,
-            TerminalCompositor,
-            TerminalEvent,
-            make_label,
-            TerminalView,
-            TerminalEditor},
-    }
-};
-
-pub struct AsciiBox {
-    content: Option<Arc<dyn TerminalView>>,
-    extent: Vector2<i16>,
-
-    cast: Arc<RwLock<ObserverBroadcast<dyn TerminalView>>>
-}
-
-impl AsciiBox {
-    pub fn new(
-        extent: Vector2<i16>,
-        content_port: OuterViewPort<dyn TerminalView>,
-        output_port: InnerViewPort<dyn TerminalView>
-    ) -> Arc<RwLock<Self>> {
-        let ascii_box = Arc::new(RwLock::new(AsciiBox {
-            content: None,
-            extent,
-            cast: output_port.get_broadcast()
-        }));
-
-        output_port.0.update_hooks.write().unwrap().push(Arc::new(content_port.0.clone()));
-        output_port.set_view(Some(ascii_box.clone()));
-        content_port.add_observer(ascii_box.clone());
-
-        ascii_box
-    }
-
-    pub fn resize(&mut self, new_extent: Vector2<i16>) {
-        if self.extent != new_extent {
-            let old_extent = self.extent;
-            self.extent = new_extent;
-            self.notify_each(GridWindowIterator::from(Point2::new(0, 0) .. Point2::new(2+std::cmp::max(old_extent.x, new_extent.x), 2+std::cmp::max(old_extent.y, new_extent.y))));
-        }
-    }
-
-    pub fn fit_content(&mut self) {
-        if let Some(c) = self.content.as_ref() {
-            let p = c.range().end;
-            self.resize(Vector2::new(p.x, p.y));
-        } else {
-            self.resize(Vector2::new(0, 0));
-        }
-    }
-}
-
-impl Observer<dyn TerminalView> for AsciiBox {
-    fn reset(&mut self, new_content: Option<Arc<dyn TerminalView>>) {
-        self.content = new_content;
-        self.notify_each(GridWindowIterator::from(Point2::new(0, 0) .. Point2::new(self.extent.x+2, self.extent.y+2)));
-    }
-
-    fn notify(&mut self, pt: &Point2<i16>) {
-        self.cast.notify(&(pt + Vector2::new(1, 1)));
-    }
-}
-
-impl View for AsciiBox {
-    type Msg = Point2<i16>;
-}
-
-impl IndexView<Point2<i16>> for AsciiBox {
-    type Item = TerminalAtom;
-
-    fn get(&self, pt: &Point2<i16>) -> Option<TerminalAtom> {
-        if pt.x == 0 || pt.x == self.extent.x+1 {
-            // vertical line
-            if pt.y == 0 && pt.x == 0 {
-                Some(TerminalAtom::from('╭'))
-            } else if pt.y == 0 && pt.x == self.extent.x+1 {
-                Some(TerminalAtom::from('╮'))
-            } else if pt.y > 0 && pt.y < self.extent.y+1 {
-                Some(TerminalAtom::from('│'))
-            } else if pt.y == self.extent.y+1 && pt.x == 0 {
-                Some(TerminalAtom::from('╰'))
-            } else if pt.y == self.extent.y+1 && pt.x == self.extent.x+1 {
-                Some(TerminalAtom::from('╯'))
-            } else {                
-                None
-            }
-        } else if pt.y == 0 || pt.y == self.extent.y+1 {
-            // horizontal line
-            if pt.x > 0 && pt.x < self.extent.x+1 {
-                Some(TerminalAtom::from('─'))
-            } else {
-                None
-            }
-        } else if
-            pt.x < self.extent.x+1 &&
-            pt.y < self.extent.y+1
-        {
-            self.content.get(&(pt - Vector2::new(1, 1)))
-        } else {
-            None
-        }
-    }
-
-    fn area(&self) -> Option<Vec<Point2<i16>>> {
-        Some(GridWindowIterator::from(
-            Point2::new(0, 0) .. Point2::new(self.extent.x+2, self.extent.y+2)
-        ).collect())
-    }
-
-}
diff --git a/shell/src/main.rs b/shell/src/main.rs
index 79bc16d..c53f5ab 100644
--- a/shell/src/main.rs
+++ b/shell/src/main.rs
@@ -21,7 +21,7 @@ use{
             ObserverBroadcast,
             context::{ReprTree, Object, MorphismType, MorphismMode, Context},
             port::{UpdateTask}},
-        index::{IndexView},
+        index::{IndexView, IndexArea},
         grid::{GridWindowIterator},
         sequence::{SequenceView, SequenceViewExt},
         vec::{VecBuffer},
@@ -44,6 +44,24 @@ use{
     }
 };
 
+struct TestView {}
+
+impl View for TestView {
+    type Msg = IndexArea<Point2<i16>>;
+}
+
+impl IndexView<Point2<i16>> for TestView {
+    type Item = TerminalAtom;
+
+    fn get(&self, pt: &Point2<i16>) -> Option<TerminalAtom> {
+        Some(TerminalAtom::from('.'))
+    }
+
+    fn area(&self) -> IndexArea<Point2<i16>> {
+        IndexArea::Full
+    }
+}
+
 #[async_std::main]
 async fn main() {
     let term_port = ViewPort::new();
@@ -99,35 +117,22 @@ async fn main() {
                 tree_addr: vec![ 0 ]
             });
 
-            loop {
-                term_port.update();
-                /*
-                if let Some(p) = pty.as_mut() {
-                    if p.get_status() {
-                        if let Some(ptybox) = ptybox.take() {
-                            ptybox.write().unwrap().fit_content();
-                        }
-                        pty = None;
-                        process_list_editor.up();
+            let tp = term_port.clone();
+            async_std::task::spawn(
+                async move {
+                    loop {
+                        tp.update();
+                        async_std::task::sleep(std::time::Duration::from_millis(10)).await;
                     }
                 }
-*/
-                term_port.update();
-
+            );
+            
+            loop {
                 let ev = term.next_event().await;
-/*
-                if let Some(pty) = pty.as_mut() {
-                    pty.handle_terminal_event(&ev);
-                } else {
-*/
                 match ev {
                     TerminalEvent::Resize(new_size) => {
                         cur_size.set(new_size);
-                        term_port.inner().get_broadcast().notify_each(
-                            nested::grid::GridWindowIterator::from(
-                                Point2::new(0,0) .. Point2::new(new_size.x, new_size.y)
-                            )
-                        );
+                        term_port.inner().get_broadcast().notify(&IndexArea::Full);
                     }
                     TerminalEvent::Input(Event::Key(Key::Ctrl('c'))) |
                     TerminalEvent::Input(Event::Key(Key::Ctrl('g'))) |
@@ -157,27 +162,7 @@ async fn main() {
                         process_list_editor.goto_end();
                     }
                     TerminalEvent::Input(Event::Key(Key::Char('\n'))) => {
-                        //let mut output_port = ViewPort::new();
                         process_list_editor.get_item().unwrap().write().unwrap().launch_pty2();
-/*
-                        let box_port = ViewPort::new();                        
-                        let test_box = AsciiBox::new(
-                            Vector2::new(80, 25),
-                            output_port.outer()
-                                .map_item(|_,a| a.add_style_back(TerminalStyle::fg_color((230, 230, 230)))),
-                            box_port.inner()
-                        );
-
-                        ptybox = Some(test_box.clone());
-
-                        table_buf.remove(Point2::new(0, y-1));
-
-                        let mut p = box_port.outer().map_item(|_idx, x| x.add_style_back(TerminalStyle::fg_color((90, 120, 100)))                            .offset(Vector2::new(0, -1));
-                        table_port.update_hooks.write().unwrap().push(Arc::new(p.clone().0));
-
-                        y += 1;
-                        table_buf.insert(Point2::new(0, y), p.clone());
-*/
                     }
 
                     ev => {
@@ -229,7 +214,8 @@ async fn main() {
                 }
             }
 
-            //drop(term);
+            drop(term);
+            drop(term_port);
         }
     );
 
diff --git a/shell/src/process.rs b/shell/src/process.rs
index 0bb63fc..70b3d6c 100644
--- a/shell/src/process.rs
+++ b/shell/src/process.rs
@@ -134,10 +134,6 @@ impl ProcessLauncher {
 
     pub fn launch_pty2(&mut self) {
         self.launch_pty(self.pty_port.inner());
-        //self.ptybox.write().unwrap().fit_content();
-
-        //let mut p =
-        //table_port.update_hooks.write().unwrap().push(Arc::new(p.clone().0));
     }
 
     pub fn launch_pty(&mut self, port: InnerViewPort<dyn TerminalView>) -> Option<crate::pty::PTY> {