Hey ArenMook,
Fair enough - I guess your great support made me lazy.
So concluding, the edit in my post was actually essential.
Removing a widget is fine, it works fine, even in a static panel.
Moving is a different story as widgets can not scale, rotate or translate while in a static panel.
I can work with this. I'll give every building a widget all in one static UIPanel, which I'll disable on tap, while enabling a separate widget (for only that building) which tweens.
Thanks again ArenMook for the great support!