tiling: Allow direction to be reversed

src/shell/layout/tiling/mod.rs

@@ -95,6 +95,18 @@ pub enum Direction {
     Down,
 }
 
+impl std::ops::Not for Direction {
+    type Output = Self;
+    fn not(self) -> Self::Output {
+        match self {
+            Direction::Left => Direction::Right,
+            Direction::Right => Direction::Left,
+            Direction::Up => Direction::Down,
+            Direction::Down => Direction::Up,
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum FocusResult {
     None,