On Windows, Remove WS_CAPTION, WS_BORDER and WS_EX_WINDOWEDGE styles for child windows (#3410)

CHANGELOG.md

@@ -34,6 +34,7 @@ Unreleased` header.
 - **Breaking:** Rename `TouchpadMagnify` to `PinchGesture`, `SmartMagnify` to `DoubleTapGesture` and `TouchpadRotate` to `RotationGesture` to represent the action rather than the intent.
 - on iOS, add detection support for `PinchGesture`, `DoubleTapGesture` and `RotationGesture`.
 - on Windows: add `with_border_color`, `with_title_background_color`, `with_title_text_color` and `with_corner_preference`
+- On Windows, Remove `WS_CAPTION`, `WS_BORDER` and `WS_EX_WINDOWEDGE` styles for child windows without decorations.
 
 # 0.29.10
 

src/platform_impl/windows/window_state.rs

@@ -279,6 +279,12 @@ impl WindowFlags {
         }
         if self.contains(WindowFlags::CHILD) {
             style |= WS_CHILD; // This is incompatible with WS_POPUP if that gets added eventually.
+
+            // Remove decorations window styles for child
+            if !self.contains(WindowFlags::MARKER_DECORATIONS) {
+                style &= !(WS_CAPTION | WS_BORDER);
+                style_ex &= !WS_EX_WINDOWEDGE;
+            }
         }
         if self.contains(WindowFlags::POPUP) {
             style |= WS_POPUP;