input: Allow Escape to cancel grabs

src/config/key_bindings.rs

@@ -143,6 +143,8 @@ pub enum Action {
     Terminate,
     Debug,
     Close,
+    #[serde(skip)]
+    Escape,
 
     Workspace(u8),
     NextWorkspace,
@@ -317,4 +319,11 @@ pub fn add_default_bindings(
         output_next.iter().copied(),
         Action::MoveToOutput(output_next_dir),
     );
+
+    insert_binding(
+        key_bindings,
+        KeyModifiers::default(),
+        std::iter::once(Keysym::Escape),
+        Action::Escape,
+    );
 }