One thing to be aware of here is that there is a difference between the mouse, with all of the interaction your computer does with it, and the cursor position on the screen. Trying to get the actual data passed by the mouse is resource intensive and complicated. On the other hand, letting the OS do its job and just getting the result of the cursor location in a window is much easier and uses a lot less CPU cycles.
The example above demonstrates getting the information from a window, with all the heavy lifting already done upstream.