SDL - how to enable window (surface) repaint

hello,

i am using sdl library from Ruby/SDL.

the problem is that if the sdl window is overlapped with another
window(s)
and then “switched” back, the surface of sdl has blank portion (where
the
overlapping window was.

i am guessing that i need to hook into some event and do refresh but
how? i
googled but not successfully…

vlad

forgot to tell - i am drawing pixels…

vlad

solved, all it needed was an event loop, my humble apologies for wasted
bandwitch and your time…

vlad