/// <inheritdoc cref="GLOFC.GL4.Controls.GLBaseControl.Add(GLBaseControl, bool)"/>
public override void Add(GLBaseControl child, bool atback = false)
{
// On control add, to display, we need to do more work to set textures up and note the bitmap size
// textures will be updated on invalidatelayout
System.Diagnostics.Debug.Assert(child is GLScrollPanel == false, "GLScrollPanel must not be a child of GLForm");
textures[child] = items.NewTexture2D(null); // we make a texture per top level control to render with
size[child] = child.Size;
visible[child] = child.Visible;
child.MakeLevelBitmap(Math.Max(1, child.Width), Math.Max(1, child.Height)); // ensure we make a bitmap
base.Add(child, atback);
}