[racket] Graphical Toolkit change question

At Thu, 24 Feb 2011 09:30:26 +0100, "Christophe Vandenberghe" wrote:
> But then again like I said before. It would be easier to have
> transparency for panels, as it would resolve the need for panes
> inserted in panels to be able to hide or delete them when needed.
> That would also solve the background problem. Would that be easy to
> achieve with the new implementation?

I'm not clear on the sense in which panels are currently opaque.

Since siblings are not supposed to overlap, the only kind of window
that can be behind a panel is another panel or eventually a frame.
I'm relatively clear on what happens with Win32 and Cocoa:

 * Under Win32 (the way `racket/gui' currently uses it), all panels and
   frames are the same color, so you can't really tell whether panels
   are transparent (i.e., transparent and solid is all the same).

 * Under Cocoa, all panels are transparent, allowing a frame's texture
   (if any) to show through.

Is there a Gtk theme where frame content and/or panels can be textured
(as opposed to being all the same color), so that you can tell the
difference between an opaque panel and a transparent one? Or are you
talking about something else completely?