Hey Mark
Best, Source, and AEPrint Views are unavailable to the in-window result panel unless you click in it first.
This is different than Script Debugger 5.x.
I have keyboard shortcuts for all of these and am used to easily toggling between them.
They work fine in the dedicated Result Explorer Window.
Script Debugger 6.0.1 (6A175) on OSX 10.11.5.
-Chris