Add mouse events listener for Widgets

[AlexandreK38]

Hi,
I wanted to add a mouse scroll listener on the UIScrollView to be able to scroll with the mouse. Basically it works, but if we have several scroll views then they will all move, even if the mouse is not over them.

To be able to have only the top widget to handle the mouse scroll and not others, we need to implement the same touches events mechanism but for mouse events. So this will work for scroll event, but also press, released, and moved.
We can also, as for touches, add a listener to our own widgets.

[AlexandreK38]

I forgot about the extensions, I'll need to fix them with the new code