In some cases aglSwapBuffers doesn't update screen. However when mouse pressed in window, it's updated without any re-render.
No luck with caatch update moment/call in debugger. For example if stop on breakpoint - screen is already updated, but if go step by step - not updated yet. In past a bit similar prob was solved with set AGL_SWAP_INTERVAL = 1, but now it has no effect.
I realize agl framework is totally obsolete but we need a refactoring to get rid of it, that is what I'm doing now.