collisions with objects!

hi, i need some help to work out how to detect collisions between two objects in a 2d window, at the moment the user is able to move an object around the window and there are many objects at all different heights coming from the right! Can anyone give me some help to make the window exit if the object the user is controlling collides with one of the objects coming from the right?

This is not an OpenGL question, what you need are intersection-tests (that’s a physics-problem).