linux/x11: Restore differentiation of mouse/keyboard focus (#13995)

This restores https://github.com/zed-industries/zed/pull/13943 which was
reverted in #13974 because it was possible to get in a state where focus
could not be restored on a window.

In this PR there's an additional change: `FocusIn` and `FocusOut` events
are always handled, even if the `event.mode` is not "NORMAL". In my
testing, `alt-tabbing` between windows didn't produce `FocusIn` and
`FocusOut` events when we had that check. Now, with the check removed,
it's possible to switch focus between two windows again with `alt-tab`.


Release Notes:

- N/A

---------

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/gpui/src/platform/linux/wayland/client.rs

@@ -1403,6 +1403,7 @@ impl Dispatch<wl_pointer::WlPointer, ()> for WaylandClientStatePtr {
 
                 if let Some(window) = get_window(&mut state, &surface.id()) {
                     state.mouse_focused_window = Some(window.clone());
+
                     if state.enter_token.is_some() {
                         state.enter_token = None;
                     }
@@ -1416,7 +1417,7 @@ impl Dispatch<wl_pointer::WlPointer, ()> for WaylandClientStatePtr {
                         }
                     }
                     drop(state);
-                    window.set_focused(true);
+                    window.set_hovered(true);
                 }
             }
             wl_pointer::Event::Leave { .. } => {
@@ -1432,7 +1433,7 @@ impl Dispatch<wl_pointer::WlPointer, ()> for WaylandClientStatePtr {
 
                     drop(state);
                     focused_window.handle_input(input);
-                    focused_window.set_focused(false);
+                    focused_window.set_hovered(false);
                 }
             }
             wl_pointer::Event::Motion {

crates/gpui/src/platform/linux/wayland/window.rs

@@ -36,6 +36,7 @@ pub(crate) struct Callbacks {
     request_frame: Option<Box<dyn FnMut()>>,
     input: Option<Box<dyn FnMut(crate::PlatformInput) -> crate::DispatchEventResult>>,
     active_status_change: Option<Box<dyn FnMut(bool)>>,
+    hover_status_change: Option<Box<dyn FnMut(bool)>>,
     resize: Option<Box<dyn FnMut(Size<Pixels>, f32)>>,
     moved: Option<Box<dyn FnMut()>>,
     should_close: Option<Box<dyn FnMut() -> bool>>,
@@ -97,6 +98,7 @@ pub struct WaylandWindowState {
     client: WaylandClientStatePtr,
     handle: AnyWindowHandle,
     active: bool,
+    hovered: bool,
     in_progress_configure: Option<InProgressConfigure>,
     in_progress_window_controls: Option<WindowControls>,
     window_controls: WindowControls,
@@ -181,6 +183,7 @@ impl WaylandWindowState {
             appearance,
             handle,
             active: false,
+            hovered: false,
             in_progress_window_controls: None,
             // Assume that we can do anything, unless told otherwise
             window_controls: WindowControls {
@@ -700,6 +703,12 @@ impl WaylandWindowStatePtr {
         }
     }
 
+    pub fn set_hovered(&self, focus: bool) {
+        if let Some(ref mut fun) = self.callbacks.borrow_mut().hover_status_change {
+            fun(focus);
+        }
+    }
+
     pub fn set_appearance(&mut self, appearance: WindowAppearance) {
         self.state.borrow_mut().appearance = appearance;
 
@@ -845,6 +854,10 @@ impl PlatformWindow for WaylandWindow {
         self.borrow().active
     }
 
+    fn is_hovered(&self) -> bool {
+        self.borrow().hovered
+    }
+
     fn set_title(&mut self, title: &str) {
         self.borrow().toplevel.set_title(title.to_string());
     }
@@ -899,6 +912,10 @@ impl PlatformWindow for WaylandWindow {
         self.0.callbacks.borrow_mut().active_status_change = Some(callback);
     }
 
+    fn on_hover_status_change(&self, callback: Box<dyn FnMut(bool)>) {
+        self.0.callbacks.borrow_mut().hover_status_change = Some(callback);
+    }
+
     fn on_resize(&self, callback: Box<dyn FnMut(Size<Pixels>, f32)>) {
         self.0.callbacks.borrow_mut().resize = Some(callback);
     }