/// <summary>Paints the overlay</summary>
protected void PaintHighlight(Graphics gfx, Rectangle win_rect, Rectangle highlight_rect)
{
// Paint the blue layer
highlight_rect.Inflate(2, 2);
using (gfx.SaveState())
{
gfx.SetClip(highlight_rect, CombineMode.Exclude);
using (var b = Gdi.CreateRadialGradientBrush(highlight_rect.Centre(), 500, 500, Color.FromArgb(0xA0, Color.DarkBlue), Color.FromArgb(0x10, Color.LightSkyBlue)))
gfx.FillRectangle(b, win_rect);
}
// Draw a border
using (var pen0 = new Pen(Color.DarkBlue, 3f))
using (var pen1 = new Pen(Color.LightSkyBlue, 5f))
{
gfx.DrawRectangle(pen0, highlight_rect);
highlight_rect.Inflate(5, 5);
gfx.DrawRectangle(pen1, highlight_rect);
}
}