I believe the answer to both questions is the video card playing badly with OpenGL. For the sticky key, QB64 is probably reading from the buffer passed by the os to opengl and it's lagging. For the bad mouse aim, you probably get a black bar on top of the window, right below the title bar, which means opengl is trying to place the window buffer but the os is offsetting it. For the first issue I don't see a quick solution. For the second, just don't maximize your window, but instead resize it manually so it fills your screen but doesn't give you the offset bug.