fix(wm): fix unresponsiveness by using asynchronous window handling

Unresponsive windows might cause Komorebi to hang because functions like
SetWindowPos wait for the target window's WindowProc.

I changed most SetWindowPos calls to use the SWP_ASYNCWINDOWPOS flag,
which should avoid hanging, and I changed the one
WindowsApi::move_window call to use position_window instead. I also
changed the ShowWindow to ShowWindowAsync.

The only issue I noticed was that it caused the stackbar to disappear
(and/or flicker), probably because the window is modified right after
moving it, so I disabled the async position_window for that.

komorebi/src/stackbar_manager/stackbar.rs

@@ -180,7 +180,9 @@ impl Stackbar {
         layout.top -= workspace_specific_offset + STACKBAR_TAB_HEIGHT.load_consume();
         layout.left -= workspace_specific_offset;
 
-        WindowsApi::position_window(self.hwnd, &layout, false)?;
+        // Async causes the stackbar to disappear or flicker because we modify it right after,
+        // so we have to do a synchronous call
+        WindowsApi::position_window(self.hwnd, &layout, false, false)?;
 
         unsafe {
             let hdc = GetDC(Option::from(self.hwnd()));

komorebi/src/window.rs

@@ -203,16 +203,15 @@ impl RenderDispatcher for MovementRenderDispatcher {
     fn render(&self, progress: f64) -> Result<()> {
         let new_rect = self.start_rect.lerp(self.target_rect, progress, self.style);
 
-        // using MoveWindow because it runs faster than SetWindowPos
+        // MoveWindow runs faster than SetWindowPos, but it doesn't support async window pos
-        // so animation have more fps and feel smoother
+        WindowsApi::position_window(self.hwnd, &new_rect, self.top, true)?;
-        WindowsApi::move_window(self.hwnd, &new_rect, false)?;
         WindowsApi::invalidate_rect(self.hwnd, None, false);
 
         Ok(())
     }
 
     fn post_render(&self) -> Result<()> {
-        WindowsApi::position_window(self.hwnd, &self.target_rect, self.top)?;
+        WindowsApi::position_window(self.hwnd, &self.target_rect, self.top, true)?;
         if ANIMATION_MANAGER
             .lock()
             .count_in_progress(MovementRenderDispatcher::PREFIX)
@@ -467,7 +466,7 @@ impl Window {
 
             AnimationEngine::animate(render_dispatcher, duration)
         } else {
-            WindowsApi::position_window(self.hwnd, layout, top)
+            WindowsApi::position_window(self.hwnd, layout, top, true)
         }
     }
 

komorebi/src/window_manager.rs

@@ -1517,7 +1517,7 @@ impl WindowManager {
                             }
                         }
 
-                        WindowsApi::position_window(window.hwnd, &rect, false)?;
+                        WindowsApi::position_window(window.hwnd, &rect, false, true)?;
                         if mouse_follows_focus {
                             WindowsApi::center_cursor_in_rect(&rect)?;
                         }
@@ -2521,7 +2521,7 @@ impl WindowManager {
                     }
                 }
 
-                WindowsApi::position_window(window.hwnd, &rect, false)?;
+                WindowsApi::position_window(window.hwnd, &rect, false, true)?;
                 if mouse_follows_focus {
                     WindowsApi::center_cursor_in_rect(&rect)?;
                 }

komorebi/src/windows_api.rs

@@ -105,7 +105,7 @@ use windows::Win32::UI::WindowsAndMessaging::SetForegroundWindow;
 use windows::Win32::UI::WindowsAndMessaging::SetLayeredWindowAttributes;
 use windows::Win32::UI::WindowsAndMessaging::SetWindowLongPtrW;
 use windows::Win32::UI::WindowsAndMessaging::SetWindowPos;
-use windows::Win32::UI::WindowsAndMessaging::ShowWindow;
+use windows::Win32::UI::WindowsAndMessaging::ShowWindowAsync;
 use windows::Win32::UI::WindowsAndMessaging::SystemParametersInfoW;
 use windows::Win32::UI::WindowsAndMessaging::WindowFromPoint;
 use windows::Win32::UI::WindowsAndMessaging::CW_USEDEFAULT;
@@ -125,6 +125,7 @@ use windows::Win32::UI::WindowsAndMessaging::SPI_GETACTIVEWINDOWTRACKING;
 use windows::Win32::UI::WindowsAndMessaging::SPI_GETFOREGROUNDLOCKTIMEOUT;
 use windows::Win32::UI::WindowsAndMessaging::SPI_SETACTIVEWINDOWTRACKING;
 use windows::Win32::UI::WindowsAndMessaging::SPI_SETFOREGROUNDLOCKTIMEOUT;
+use windows::Win32::UI::WindowsAndMessaging::SWP_ASYNCWINDOWPOS;
 use windows::Win32::UI::WindowsAndMessaging::SWP_NOMOVE;
 use windows::Win32::UI::WindowsAndMessaging::SWP_NOSIZE;
 use windows::Win32::UI::WindowsAndMessaging::SWP_SHOWWINDOW;
@@ -473,7 +474,12 @@ impl WindowsApi {
     /// position window resizes the target window to the given layout, adjusting
     /// the layout to account for any window shadow borders (the window painted
     /// region will match layout on completion).
-    pub fn position_window(hwnd: isize, layout: &Rect, top: bool) -> Result<()> {
+    pub fn position_window(
+        hwnd: isize,
+        layout: &Rect,
+        top: bool,
+        async_window_pos: bool,
+    ) -> Result<()> {
         let hwnd = HWND(as_ptr!(hwnd));
 
         let mut flags = SetWindowPosition::NO_ACTIVATE
@@ -484,6 +490,14 @@ impl WindowsApi {
         // If the request is to place the window on top, then HWND_TOP will take
         // effect, otherwise pass NO_Z_ORDER that will cause set_window_pos to
         // ignore the z-order paramter.
+
+        // By default SetWindowPos waits for target window's WindowProc thread
+        // to process the message, so we have to use ASYNC_WINDOW_POS to avoid
+        // blocking our thread in case the target window is not responding.
+        if async_window_pos {
+            flags |= SetWindowPosition::ASYNC_WINDOW_POS;
+        }
+
         if !top {
             flags |= SetWindowPosition::NO_Z_ORDER;
         }
@@ -521,7 +535,8 @@ impl WindowsApi {
         let flags = SetWindowPosition::NO_MOVE
             | SetWindowPosition::NO_SIZE
             | SetWindowPosition::NO_ACTIVATE
-            | SetWindowPosition::SHOW_WINDOW;
+            | SetWindowPosition::SHOW_WINDOW
+            | SetWindowPosition::ASYNC_WINDOW_POS;
 
         let position = HWND_TOP;
         Self::set_window_pos(
@@ -538,7 +553,8 @@ impl WindowsApi {
         let flags = SetWindowPosition::NO_MOVE
             | SetWindowPosition::NO_SIZE
             | SetWindowPosition::NO_ACTIVATE
-            | SetWindowPosition::SHOW_WINDOW;
+            | SetWindowPosition::SHOW_WINDOW
+            | SetWindowPosition::ASYNC_WINDOW_POS;
 
         let position = HWND_BOTTOM;
         Self::set_window_pos(
@@ -555,6 +571,7 @@ impl WindowsApi {
                 | SetWindowPosition::NO_ACTIVATE
                 | SetWindowPosition::NO_REDRAW
                 | SetWindowPosition::SHOW_WINDOW
+                | SetWindowPosition::ASYNC_WINDOW_POS
         };
 
         Self::set_window_pos(
@@ -581,6 +598,7 @@ impl WindowsApi {
         .process()
     }
 
+    /// move_windows calls MoveWindow, but cannot be called with async window pos, so it might hang
     pub fn move_window(hwnd: isize, layout: &Rect, repaint: bool) -> Result<()> {
         let hwnd = HWND(as_ptr!(hwnd));
 
@@ -599,7 +617,7 @@ impl WindowsApi {
         // https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-showwindow
         // TODO: error handling
         unsafe {
-            let _ = ShowWindow(HWND(as_ptr!(hwnd)), command);
+            let _ = ShowWindowAsync(HWND(as_ptr!(hwnd)), command);
         };
     }
 
@@ -656,7 +674,7 @@ impl WindowsApi {
                 0,
                 0,
                 0,
-                SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW,
+                SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW | SWP_ASYNCWINDOWPOS,
             )
             .process();
             SetForegroundWindow(HWND(as_ptr!(hwnd)))