composite manager and memory mgmt

[Tapani Pälli]

Hello,
I'm trying to build a sort of 'resource friendly' composite manager for
Maemo platform, code is based on xcompmgr code. I added another thread
that does some memory management keeping up a 'reasonable cache' of
renderpictures. Basically it frees pictures for every application window
that is not currently visible on the screen (pictures for windows that
are under current application window [1])

Do you think this is a good approach? Should I free memory only when
something happens ('event based') or is threading safe option here?

If you have any suggestions of better memory mgmt model or any comments
please mail!

// Tapani

[1] In Maemo platform, only one application window (with it's menus and
dialogs) is visible at time