GuiTabBookCtrl and GuiTabPageCtrl

I've got a GuiTabBookCtrl setup with 13 tabs and it seems to be working fine. I need to have a 'GuiControlListPopUp' menu update to a different list depending on which tab is selected in my GuiTabBookCtrl. Anyone know how I can add my own actions to the 'tab selection' code? I don't even know where to look to modify that...

I'm also going to need my GuiObjectView to load a different DTS shape each time an item from the GuiControlListPopUp is selected and could use some help making that happen as well...

Thanks in advance for any help!