Keeping things moving during Win32 Move/Resize events

Hi everybody.

As many of you will know, windows move/resize events use their own message pumps, effectively blocking the host application until the operation has completed.

To keep animations running in the background we have to use SetTimer/KillTimer to keep things ticking over.

This works well, except for when the user mouse-downs on a window caption without moving the mouse.

In this case there's an annoying 500ms delay right after windows sends a WM_SYSCOMMAND with (SC_MOVE|HTCAPTION).

switch (msg) {
	case WM_NCLBUTTONDOWN:
		if (SendMessage(hWnd, WM_NCHITTEST, wParam, lParam) == HTCAPTION) {
			POINT point;
			GetCursorPos(&point);
			ScreenToClient(hWnd, &point);
			PostMessage(hwnd, WM_MOUSEMOVE, 0, point.x | point.y << 16);
		}
		break;
	case WM_ENTERSIZEMOVE:
		SetTimer(hWnd, 1, 0, NULL);
		return 0;
	case WM_EXITSIZEMOVE:
		KillTimer(hWnd, 1);
		return 0;
	case WM_TIMER:
		UpdateAndRedraw()
		return 0;
	case ...
}