the thing is that I''m writing a program that draws lines on screen with mouse clicks the problem is that the screen isnt refreshing unless I''m pressing the ALT+TAB keys twice I use glFlush() command and I dont know what else is missing.

if u''re using win32, make sure u render the scene in the main loop or the message loop every pass.
give some more information.... how do u render...
glFlush() will not draw without the rendering loop...