Hi Chris,
I'm not an Ultrix expert, so I don't have the whole answer for you, but perhaps I can point you in the right direction.
Wat you can do is look at how the panel you like implemented it.
If you go to the "Group Category Soft Panel" you mention and go into "PanelBuilder Edit Mode", you can <Shift> + Double Click on an element. It will show you the underlying source that is used for that element.
Something like this:

If you click the "Go Up" button a few times, you can actually go all the way to the top of the panel, and see the underlying source for the whole panel.
From that, you can probably reverse engineer how that panel is doing what you want, and mimic that in your panel. So if you shift-double click on a button, andyou see it's calling a function like OnClickGroup, you can then go up, and find the function "OnClickGroup" to see what it does.
Hopefully that helps.
#DashBoard