Fix Window::set_minimized(false) on Windows

When other application minimized the winit window the
minimize state was going out of sync. This commit fixes
it by polling the state in `set_minimized`.

CHANGELOG.md

@@ -8,6 +8,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- On Windows, fix `Window::set_minimized(false)` not working for windows minimized by `Win + D` hotkey.
 - **Breaking:** On Web, touch input no longer fires `WindowEvent::Cursor*`, `WindowEvent::MouseInput`, or `DeviceEvent::MouseMotion` like other platforms, but instead it fires `WindowEvent::Touch`.
 - **Breaking:** Removed platform specific `WindowBuilder::with_parent` API in favor of `WindowBuilder::with_parent_window`.
 - On Windows, retain `WS_MAXIMIZE` window style when un-minimizing a maximized window.

src/platform_impl/windows/window.rs

@@ -40,7 +40,7 @@ use windows_sys::Win32::{
         },
         WindowsAndMessaging::{
             CreateWindowExW, FlashWindowEx, GetClientRect, GetCursorPos, GetForegroundWindow,
-            GetSystemMetrics, GetWindowPlacement, GetWindowTextLengthW, GetWindowTextW,
+            GetSystemMetrics, GetWindowPlacement, GetWindowTextLengthW, GetWindowTextW, IsIconic,
             IsWindowVisible, LoadCursorW, PeekMessageW, PostMessageW, RegisterClassExW, SetCursor,
             SetCursorPos, SetForegroundWindow, SetWindowDisplayAffinity, SetWindowPlacement,
             SetWindowPos, SetWindowTextW, CS_HREDRAW, CS_VREDRAW, CW_USEDEFAULT, FLASHWINFO,
@@ -462,8 +462,13 @@ impl Window {
         let window = self.window.clone();
         let window_state = Arc::clone(&self.window_state);
 
+        let is_minimized = self.is_minimized();
+
         self.thread_executor.execute_in_thread(move || {
             let _ = &window;
+            WindowState::set_window_flags_in_place(&mut window_state.lock().unwrap(), |f| {
+                f.set(WindowFlags::MINIMIZED, is_minimized)
+            });
             WindowState::set_window_flags(window_state.lock().unwrap(), window.0, |f| {
                 f.set(WindowFlags::MINIMIZED, minimized)
             });
@@ -489,6 +494,11 @@ impl Window {
         window_state.window_flags.contains(WindowFlags::MAXIMIZED)
     }
 
+    #[inline]
+    pub fn is_minimized(&self) -> bool {
+        unsafe { IsIconic(self.hwnd()) == 1 }
+    }
+
     #[inline]
     pub fn fullscreen(&self) -> Option<Fullscreen> {
         let window_state = self.window_state_lock();