public void Copy()
{
if (ActiveSurface != null && ActiveSurface.Selection != null)
{
var selection = ActiveSurface.Selection.Value;
copyBrush = new TileBrush(selection.Width, selection.Height);
for (int ty = selection.Y; ty < selection.Bottom; ty++)
{
for (int tx = selection.X; tx < selection.Right; tx++)
{
copyBrush.AddTile(ActiveSurface.Screen.TileAt(tx, ty), tx - selection.X, ty - selection.Y);
}
}
}
}