I like the possibility with favorites, where you can make a dynamic button that allows for left-right-clicking to open items in either left- or right-side pane:
Favorites FILTER "(%CLOUDPATH%\3D\Blender|%CLOUDPATH%\3D\ZBrush|%CLOUDPATH%\3D\Maya)" NEWTAB=findexisting,tofront NOOPENINTABS USEQUALKEYS MULTIFUNC=tabs SHOWICONS
However, I wish to be able to Customize > drag folder to toolbar and then be able to assign said left-/right-click to open in either pane for normal buttons as well.