[GtkGLExt] Sharing display lists + textures

[<lindleyf cox net>]

At first glance, GtkGLExt supports a simple interface for sharing display lists and textures, which is nice. However, when I actually try to use it, I've run into several practical problems and I was hoping for some advice on ways to solve them.

I have a GUI which can contain a list of items to be viewed, and zero or more figure windows in which to view them. I use GtkGLExt to draw the items in the figure windows using OpenGL.

For efficiency, there are some things (texture downloads, display list generation) which I'd prefer to only do once the first time something is viewed, and then just re-use, even if the item is displayed in a different figure window, so it makes sense to share display lists + textures between the contexts underlying each GtkDrawingArea.

I've figured out a way to do it....provided the first figure window stays open. All the other figure windows share with the context from there. But if that figure closes, then any windows currently existing seem to be all right, but new ones created later don't handle the textures properly. The closed windows are not actually destroyed, merely gtk_widget_hide()en, but merely unrealizing them seems to be enough to destroy the GdkGLContext.

I've long thought that the biggest design flaw in OpenGL is the difficulty of creating a context without a window to attach it to. If I could just create a "window-less" context then I'd be fine, but that seems to be quite difficult using the GtkGLExt interface.

So my question is, first, has anyone encountered this type of problem before? And second, what actually happens when I share textures/display lists? If I create a texture in context A, then tell context B to share with A, then destroy context A, then create context C and tell C to share with B----will that texture be available to C or not?