Is there a way to center icons (across the entire toolbar) on a custom toolbar? If not, I would like to make that a feature request. Flexible space is not a help for this.
Use spacers in both sides, that would do!
I noted in the OP that that won't work. When a lister is resized, I want the icons to remain in the center of the toolbar.
put these spacers left and right to center the buttons
Yay! That worked. Thank you.