remove WindowFlags::MAXIMIZED from diff if we are hiding

src/platform_impl/windows/window_state.rs

@@ -239,7 +239,19 @@ impl WindowFlags {
     self = self.mask();
     new = new.mask();
 
-    let diff = self ^ new;
+    let mut diff = self ^ new;
+
+    // when hiding a maximized window, `self` contains `WindowFlags::MAXIMIZED`
+    // but `new` won't have it as it is removed in `new.mask()` call by applying `WindowFlags::INVISIBLE_AND_MASK`
+    // so `diff` will contain `WindowFlags::MAXIMIZED` and that will cause the window to unmaximize, but
+    // since we are trying to hide the window, we need to apply `WindowFlags::INVISIBLE_AND_MASK` on `diff` too.
+    if diff.contains(WindowFlags::MAXIMIZED)
+        && diff.contains(WindowFlags::VISIBLE)
+        && !new.contains(WindowFlags::VISIBLE)
+    {
+        diff &= WindowFlags::INVISIBLE_AND_MASK;
+    }
+
     if diff == WindowFlags::empty() {
       return;
     }
@@ -274,12 +286,14 @@ impl WindowFlags {
     }
 
     if diff.contains(WindowFlags::MAXIMIZED) || new.contains(WindowFlags::MAXIMIZED) {
-      unsafe {
-        if new.contains(WindowFlags::MAXIMIZED) {
-          ShowWindow(window, SW_MAXIMIZE);
-        } else if new.contains(WindowFlags::VISIBLE) {
-          ShowWindow(window, SW_RESTORE);
-        }
+       unsafe {
+        ShowWindow(
+          window,
+          match new.contains(WindowFlags::MAXIMIZED) {
+            true => SW_MAXIMIZE,
+            false => SW_RESTORE,
+          },
+        );
       }
     }