I would like to make a suggestion for a future AGS release.
I have been investigating the RAWxxx functions and I detected that a RAWRECTANGLE, CIRCLE, etc does not appear to work under the GUIs.
I mean, when I call a GUI and want to draw a rectangle on it, for example, it is drawn at the background screen, not on the GUI. Is there a way I can draw the RAW-shapes under GUIs?
It's my suggestion! :)
I believe that GUIs appearing in front of everything else is intended as a feature, and generally preferable to the alternative.
Whether it would be worth having both I couldn't say, but here's an idea that may let you do what you require for now ... assuming it works:
Make the drawable areas of your GUI transparent (index 0), and draw behind them. They would still be clickable.
Actually that may involve rawdrawing on sprites, which is prolly a complicated stuffs, some discussions had been started for that, but not a standalone thread yet, I'll start it soon.
I'm not too happy about adding raw drawing support for GUIs - there are usually cleaner ways to do what you want by using the available GUI controls.
As Gilbert says, it can be considered as part of the dynamic sprite suggestion.
I was thinking that the intended use might only involve rendering something on the GUI while open, based on some variable game properties, without actually saving the image.