Pretty much title, if you are editing a building group you can freely switch between the Buildings and Scenery tabs whilst still remaining in the building group edit mode. Clicking the Toolkit items tab force exits you from the building you're currently editing meaning that the TMT items need to either be found in the other tabs or they need to be manually added into the building group your working on.
Goes without saying that in the current times of tabs taking a long time to open - as well as clicking to edit groups, saving one of two clicks of this can add up to saved minutes very very quickly, and I think we all know and agree that manipulating items inside groups gives us much stronger tools to edit and manipulate the objects around.

Goes without saying that in the current times of tabs taking a long time to open - as well as clicking to edit groups, saving one of two clicks of this can add up to saved minutes very very quickly, and I think we all know and agree that manipulating items inside groups gives us much stronger tools to edit and manipulate the objects around.