The problem:

When using monitors which have a different resolution, attempting to move the mouse between them can be frustrating, if you're on a bigger monitor, and are "out of bounds" from the other monitor, windows will prevent you from moving over. It acts like an invisible wall, and can be a real pain.

Common scenario:

Monitor 1 (laptop monitor, on the left), Resolution 1366 x 768
Monitor 2 (external monitor, on the right), Resolution 1280 x 1024 <- larger vertically than Monitor 1

(The monitors are aligned at their tops)

Keep the mouse to the bottom of Monitor 2, and try dragging left into Monitor 1, you will not be able to do so without moving the mouse up to height 768.

The request:

Have an option, so that when you move to the left in the "out of bounds" area, it will pretend that you are at the bottom height of Monitor 1 and allow the move. This should also work when for example you are dragging a window.

This will make for a much more fluid experience, saving you from ramming your cursor against this invisible wall, or not realising and wondering why your mouse hasn't moved over to the other monitor.

I agree with you. What's even more annoying is when your monitors are the same size vertically, but have different vertical resolutions.