I have a flutter game on Windows that can start up in either fullscreen or windowed mode depending on user settings. If it stats in fullscreen, the window is created with WS_POPUP window style passed to the CreateWindow(). If the user prefers to go to windowed mode, I call windowManager.setFullScreen(false). This will go into windowed mode but the title bar will be hidden. If I call windowManager.setTitleBarStyle(TitleBarStyle.normal) to reveal the title bar, it is still hidden. I would expect setTitleBarStyle(.normal) to update the main window style to WS_OVERLAPPED to ensure the title bar is visible.