Adding multiple rows of buttons to Spark

I wrote a simple plugin to add buttons to Spark. Unfortunately the toolbar puts buttons all in a single row, and therefore my buttons don’t all fit in the window unless I make it full screen. I would like to have multiple rows of buttons instead of a single row. Is this possible via the existing plugin architecture? Is there a way to tell the toolbar to wrap additional button to another row? Or can I add multiple toolbars?

Any help is appreciated. Thanks!

This is more suitable in Spark Dev forum. WinSrev, current main developer/contributor has plans to change toolbar functionality (to have multirows or stack of buttons). But that’s not a near future plans.