fix(compatibility): handle cursor movements outside scroll region (#746)

* fix(compatibility): handle cursor movements outside scroll region

* style(fmt): make clippy happy

src/tests/fixtures/move_cursor_below_scroll_region

@@ -0,0 +1,42 @@
+
+1foo
+2foo
+3foo
+4foo
+5foo
+6foo
+7foo
+8foo
+9foo
+10foo
+11foo
+12foo
+13foo
+14foo
+15foo
+16foo
+17foo
+18foo
+19foo
+20foo
+21foo
+22foo
+23foo
+24foo
+25foo
+26foo
+27foo
+28foo
+29foo
+30foo
+31foo
+32foo
+33foo
+34foo
+35foo
+
+1bar
+2bar
+3bar
+4bar
+5zz

zellij-server/src/panes/grid.rs

@@ -883,14 +883,16 @@ impl Grid {
             self.viewport.push(new_row);
         }
         if self.cursor.y == self.height - 1 {
-            let row_count_to_transfer = 1;
-            transfer_rows_from_viewport_to_lines_above(
-                &mut self.viewport,
-                &mut self.lines_above,
-                row_count_to_transfer,
-                self.width,
-            );
-            self.selection.move_up(1);
+            if self.scroll_region.is_none() {
+                let row_count_to_transfer = 1;
+                transfer_rows_from_viewport_to_lines_above(
+                    &mut self.viewport,
+                    &mut self.lines_above,
+                    row_count_to_transfer,
+                    self.width,
+                );
+                self.selection.move_up(1);
+            }
             self.output_buffer.update_all_lines();
         } else {
             self.cursor.y += 1;
@@ -1051,7 +1053,11 @@ impl Grid {
                 } else {
                     0
                 };
-                self.cursor.y = std::cmp::min(scroll_region_bottom, y + y_offset);
+                if y >= scroll_region_top && y <= scroll_region_bottom {
+                    self.cursor.y = std::cmp::min(scroll_region_bottom, y + y_offset);
+                } else {
+                    self.cursor.y = std::cmp::min(self.height - 1, y + y_offset);
+                }
                 self.pad_lines_until(self.cursor.y, pad_character);
                 self.pad_current_line_until(self.cursor.x);
             }

zellij-server/src/panes/unit/grid_tests.rs

@@ -998,3 +998,15 @@ pub fn scroll_up_increase_width_and_scroll_down() {
     }
     assert_snapshot!(format!("{:?}", grid));
 }
+
+#[test]
+pub fn move_cursor_below_scroll_region() {
+    let mut vte_parser = vte::Parser::new();
+    let mut grid = Grid::new(34, 114, Palette::default());
+    let fixture_name = "move_cursor_below_scroll_region";
+    let content = read_fixture(fixture_name);
+    for byte in content {
+        vte_parser.advance(&mut grid, byte);
+    }
+    assert_snapshot!(format!("{:?}", grid));
+}

zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__move_cursor_below_scroll_region.snap

@@ -0,0 +1,41 @@
+---
+source: zellij-server/src/panes/./unit/grid_tests.rs
+expression: "format!(\"{:?}\", grid)"
+
+---
+00 (C): 7foo
+01 (C): 8foo
+02 (C): 9foo
+03 (C): 10foo
+04 (C): 11foo
+05 (C): 12foo
+06 (C): 13foo
+07 (C): 14foo
+08 (C): 15foo
+09 (C): 16foo
+10 (C): 17foo
+11 (C): 18foo
+12 (C): 19foo
+13 (C): 20foo
+14 (C): 21foo
+15 (C): 22foo
+16 (C): 23foo
+17 (C): 24foo
+18 (C): 25foo
+19 (C): 26foo
+20 (C): 27foo
+21 (C): 28foo
+22 (C): 29foo
+23 (C): 30foo                                                                                                             
+24 (C): 31foo                                                                                                             
+25 (C): 32foo                                                                                                             
+26 (C): 33foo                                                                                                             
+27 (C): 34foo                                                                                                             
+28 (C): 35foo                                                                                                             
+29 (C):                                                                                                                   
+30 (C):                                                                                                                   
+31 (C):                                                                                                                   
+32 (C):                                                                                                                   
+33 (C): 5zzr                                                                                                              
+34 (C): 
+