Side-click sensitive ?

This is something I was dreaming of, but not the way it happens.
I shall try to be clear. If I’m not, please let me know.

I use a 5 button mouse.
With Beta 1.3, I hoped that I would be able to use the side buttons to go forth and back between the files.
I’m used to this in OneNote as well as in my Internet browser, and I almost cannot do without.

With Beta 1.3, this did not work.
I did not beg for it, as this is not the most important thing with Scrivener.

Now, with Beta 1.4, it works, but not the way I expected.

What I would like to see is that with a side click, wherever the pointer is in the window, this would cause to jump between the files I have already browsed through (just like the arrows on top left of the editor).

What happens is that when hooving the mouse over the binder and accidentally hit one of these two side buttons, the mouse really clicks.
The application reacts on both these side buttons, as if it were a normal click.

When hooving over the editor, it sets the editor to active (I see this, as the button bar reacts each time).
Hooving over the Inspector, it activates this panel.

Beta 1.3 was not at all sensitive to these.
Beta 1.4 is sensitive to these two buttons as if they were the main mouse button (single left click).