Fix selection in scrollback

There were a few issues with selection in scrollback that were mainly
off-by-one errors. This aims at fixing these issues.

This also fixes a bug that currently exists in master where the last
cell is not selected when the mouse leaves the window to the right.

src/input.rs

@@ -278,7 +278,10 @@ impl<'a, A: ActionContext + 'a> Processor<'a, A> {
             let cell_x = (x as usize - size_info.padding_x as usize) % size_info.cell_width as usize;
             let half_cell_width = (size_info.cell_width / 2.0) as usize;
 
-            let cell_side = if cell_x > half_cell_width {
+            let cell_side = if cell_x > half_cell_width
+                // Edge case when mouse leaves the window
+                || x as f32 >= size_info.width - size_info.padding_x
+            {
                 Side::Right
             } else {
                 Side::Left

src/selection.rs

@@ -191,8 +191,6 @@ impl Selection {
             (region.end, region.start)
         };
 
-        println!("BEFORE front={:?}, start={:?}, tail={:?}, end={:?}", front, start, tail, end);
-
         if front < tail && front.line == tail.line {
             start = grid.semantic_search_left(front);
             end = grid.semantic_search_right(tail);
@@ -201,8 +199,6 @@ impl Selection {
             end = grid.semantic_search_left(tail);
         }
 
-        println!("AFTER  front={:?}, start={:?}, tail={:?}, end={:?}", front, start, tail, end);
-
         if start > end {
             ::std::mem::swap(&mut start, &mut end);
         }
@@ -249,12 +245,21 @@ impl Selection {
     }
 
     fn span_simple<G: Dimensions>(grid: &G, region: &Range<Anchor>) -> Option<Span> {
-        let start = region.start.point;
+        let mut start = region.start.point;
         let start_side = region.start.side;
-        let end = region.end.point;
+        let mut end = region.end.point;
         let end_side = region.end.side;
         let cols = grid.dimensions().col;
 
+        // Handle some edge cases
+        if start.line > end.line {
+            start.col += 1;
+            end.col -= 1;
+        } else if start.line < end.line {
+            start.col -= 1;
+            end.col += 1;
+        }
+
         let (front, tail, front_side, tail_side) = if start > end {
             // Selected upward; start/end are swapped
             (end, start, end_side, start_side)

src/term/mod.rs

@@ -1060,7 +1060,6 @@ impl Term {
         let selection = self.grid.selection.as_ref()
             .and_then(|s| s.to_span(self))
             .map(|span| {
-                // println!("span={:?}, locations={:?}", span, span.to_locations());
                 span.to_locations()
             });
         let cursor = if window_focused {