some advice Rated 5 out of 5 stars

I hope that there is a option that we can control the blank between two Button.

This review is for a previous version of the add-on ( 

You can try the newest devbuild v1.1pre2 from versions page

I've added an experimental setting to change the space between toolbar buttons that are placed on navigation toolbar.

Since sliders are not allowed for inline settings I used a menulist with predefined widths (-1px up to 20px).