When calling `Window::request_redraw` from the `RedrawRequested`
handler the `RedrawWindow` won't result in `WM_PAINT` being delivered
due since user callback is run before `DefWindowProcW` is called.
Track whether the user called `Window::request_redraw` and ask for
`RedrawWindow` after running the said function during `WM_PAINT`
handling.
Fixes#3150.
98b3508aca