private static IntPtr ComputeRoundRectRegion(int left, int top, int width, int height, int cornerRadius)
{
var nWidthEllipse = (int)(2 * cornerRadius * DpiHelper.LogicalToDeviceUnitsScalingFactorX);
var nHeightEllipse = (int)(2 * cornerRadius * DpiHelper.LogicalToDeviceUnitsScalingFactorY);
return(NativeMethods.CreateRoundRectRgn(left, top, left + width + 1, top + height + 1, nWidthEllipse,
nHeightEllipse));
}