Hello! So, my problem is this: I can compile my "Main.hs" without errors, but when I'm executing the application a black screen appears and my cursour is still visible. After klicking somewhere on the screen my normal Desktop reappears with "Hello World" in my task bar. I can minimize all other windows to have only "Hello World" visible, but the black screen appears again when I'm trying to activate the window. Do you know what I am doing wrong? Ubuntu is my OS, all libraries are installed, I have the same problem using Hugs. Here's my Main.hs: import Graphics.UI.GLUT import Graphics.Rendering.OpenGL main = do (progname, _) <- getArgsAndInitialize createWindow "Hello World" displayCallback $= display reshapeCallback $= Just reshape mainLoop reshape s@(Size w h) = do viewport $= (Position 0 0, s) postRedisplay Nothing myPoints :: [(GLfloat, GLfloat, GLfloat)] myPoints = map (\k -> (sin(2*pi*k/12),cos(2*pi*k/12),0.0)) [1..12] display = do clear [ColorBuffer] renderPrimitive Points $ mapM_ (\(x,y,z) -> vertex$Vertex3 x y z) myPoints flush Thanks for helping! :)