Toolbar separators not working correctly?

[TXCiclista]

I'm having a devil of a time getting custom toolbars to look right. It seems that as soon as I move an icon (after I've already dragged it to the bar) I might as well give up on any chance of getting it to sit "inside" a pre-existing separator. I have to drag it off the toolbar then add it again.

Is there some behavior I'm missing? I thought that if you dragged it between an icon and a separator it would stay there. Behavior seems to be that it adds a separator between itself and the other icon...

 

[Daiya Mitchell]

It might be different depending on whether you are customizing a
built-in toolbar or creating your own floating toolbar. When creating
your own, the separator is not an independent entity, rather you
right-click an icon and tell it to "begin a group" in Properties to get
a separator. I can't seem to right-click a built-in toolbar, but it
seems to operate similarly--as I move the icons that begin a group, the
separator travels with them.