Windows: apply skip taskbar state when taskbar is restarted (#2380)

src/platform_impl/windows/event_loop.rs

@@ -95,6 +95,8 @@ use crate::{
 };
 use runner::{EventLoopRunner, EventLoopRunnerShared};
 
+use super::window::set_skip_taskbar;
+
 type GetPointerFrameInfoHistory = unsafe extern "system" fn(
     pointerId: u32,
     entriesCount: *mut u32,
@@ -616,6 +618,10 @@ pub static SET_RETAIN_STATE_ON_SIZE_MSG_ID: Lazy<u32> =
     Lazy::new(|| unsafe { RegisterWindowMessageA("Winit::SetRetainMaximized\0".as_ptr()) });
 static THREAD_EVENT_TARGET_WINDOW_CLASS: Lazy<Vec<u16>> =
     Lazy::new(|| util::encode_wide("Winit Thread Event Target"));
+/// When the taskbar is created, it registers a message with the "TaskbarCreated" string and then broadcasts this message to all top-level windows
+/// <https://docs.microsoft.com/en-us/windows/win32/shell/taskbar#taskbar-creation-notification>
+pub static TASKBAR_CREATED: Lazy<u32> =
+    Lazy::new(|| unsafe { RegisterWindowMessageA("TaskbarCreated\0".as_ptr()) });
 
 fn create_event_target_window<T: 'static>() -> HWND {
     unsafe {
@@ -2181,6 +2187,10 @@ unsafe fn public_window_callback_inner<T: 'static>(
                     f.set(WindowFlags::MARKER_RETAIN_STATE_ON_SIZE, wparam != 0)
                 });
                 0
+            } else if msg == *TASKBAR_CREATED {
+                let window_state = userdata.window_state.lock();
+                set_skip_taskbar(window, window_state.skip_taskbar);
+                DefWindowProcW(window, msg, wparam, lparam)
             } else {
                 DefWindowProcW(window, msg, wparam, lparam)
             }

src/platform_impl/windows/window.rs

@@ -687,39 +687,8 @@ impl Window {
 
     #[inline]
     pub fn set_skip_taskbar(&self, skip: bool) {
-        com_initialized();
+        self.window_state.lock().skip_taskbar = skip;
-        unsafe {
+        unsafe { set_skip_taskbar(self.hwnd(), skip) };
-            TASKBAR_LIST.with(|task_bar_list_ptr| {
-                let mut task_bar_list = task_bar_list_ptr.get();
-
-                if task_bar_list.is_null() {
-                    let hr = CoCreateInstance(
-                        &CLSID_TaskbarList,
-                        ptr::null_mut(),
-                        CLSCTX_ALL,
-                        &IID_ITaskbarList,
-                        &mut task_bar_list as *mut _ as *mut _,
-                    );
-
-                    let hr_init = (*(*task_bar_list).lpVtbl).HrInit;
-
-                    if hr != S_OK || hr_init(task_bar_list.cast()) != S_OK {
-                        // In some old windows, the taskbar object could not be created, we just ignore it
-                        return;
-                    }
-                    task_bar_list_ptr.set(task_bar_list)
-                }
-
-                task_bar_list = task_bar_list_ptr.get();
-                if skip {
-                    let delete_tab = (*(*task_bar_list).lpVtbl).DeleteTab;
-                    delete_tab(task_bar_list, self.window.0);
-                } else {
-                    let add_tab = (*(*task_bar_list).lpVtbl).AddTab;
-                    add_tab(task_bar_list, self.window.0);
-                }
-            });
-        }
     }
 
     #[inline]
@@ -1106,6 +1075,40 @@ unsafe fn taskbar_mark_fullscreen(handle: HWND, fullscreen: bool) {
     })
 }
 
+pub(crate) unsafe fn set_skip_taskbar(hwnd: HWND, skip: bool) {
+    com_initialized();
+    TASKBAR_LIST.with(|task_bar_list_ptr| {
+        let mut task_bar_list = task_bar_list_ptr.get();
+
+        if task_bar_list.is_null() {
+            let hr = CoCreateInstance(
+                &CLSID_TaskbarList,
+                ptr::null_mut(),
+                CLSCTX_ALL,
+                &IID_ITaskbarList,
+                &mut task_bar_list as *mut _ as *mut _,
+            );
+
+            let hr_init = (*(*task_bar_list).lpVtbl).HrInit;
+
+            if hr != S_OK || hr_init(task_bar_list.cast()) != S_OK {
+                // In some old windows, the taskbar object could not be created, we just ignore it
+                return;
+            }
+            task_bar_list_ptr.set(task_bar_list)
+        }
+
+        task_bar_list = task_bar_list_ptr.get();
+        if skip {
+            let delete_tab = (*(*task_bar_list).lpVtbl).DeleteTab;
+            delete_tab(task_bar_list, hwnd);
+        } else {
+            let add_tab = (*(*task_bar_list).lpVtbl).AddTab;
+            add_tab(task_bar_list, hwnd);
+        }
+    });
+}
+
 unsafe fn force_window_active(handle: HWND) {
     // In some situation, calling SetForegroundWindow could not bring up the window,
     // This is a little hack which can "steal" the foreground window permission

src/platform_impl/windows/window_state.rs

@@ -49,6 +49,8 @@ pub struct WindowState {
     // Used by WM_NCACTIVATE, WM_SETFOCUS and WM_KILLFOCUS
     pub is_active: bool,
     pub is_focused: bool,
+
+    pub skip_taskbar: bool,
 }
 
 #[derive(Clone)]
@@ -152,6 +154,8 @@ impl WindowState {
 
             is_active: false,
             is_focused: false,
+
+            skip_taskbar: false,
         }
     }