Creating a second Command Panel Utilities frame?

I'd like to contain my rollouts and scripts in a frame like then Command Panel Utilities Frame where the various rollouts fit into a number of columns and the whole frame can be dynamically docked and resized specifically at column width intervals.

I tried replicating it with a Dialog registered as a DialogBar containing a number of subrollout 'columns' that is automatically sized based on the number of rollouts it has to contain. However I can not change the dimensions of a registered DialogBar.

I would have to unregister, size it, and re-register it and that isn't good. Is there a way to make it act like the utilities frame?

Is there any way I can replicate the design of the Command Panel's Utilities Frame??