I've been working with a few game oriented gui libraries trying to find a good fit. More specifically, a GUI that will work on Windows,Linux,iPhone, and Android with minimal special code.
In my tinkering I've noticed a few libraries like to render the their GUI's to an off screen texture that just display the texture instead.
Is this a common GUI technique?
Isn't there a performance hit with rapidly changing GUIs?
Were I the implementer I would have just rendered the GUI directly each frame. Is there anything particularly wrong or inefficient direct rendering?
Update: By 'game-centric GUI' I mean a GUI framework that doesn't own the window or the main loop. There are other features I'd add but the main loop is the only critical one. This usually involves various rendering backends, input injection, and an update method.