Why do you want to add an object to a group from the Objet panel, if you hace the Objet group Panel to do so?
Do not get me wrong
I am all in for your idea
But you are trading off adding multiple objects to a group for adding single object to multiple groups
I think good solution would be something like window where on one side we have available objects and on other we have objects already in said group
While on top we would have tabs with group names you are currently working on
So like if you are on Enemies group tab you are managing objects only for that group
I gonna use UI from some photo resizing program to visualize what i mean
In left side list you have available objects that can be added to group
Grayed out objects are already added to the group (or they could be simply removed from left side list if they are already on right side list)
Which is indicated by them being in right side list
On top you have Tabs with group names where you just click on tab to manage that group
Wouldn’t that be better solution?
Because we should use the context menu at the moments when we only want to quickly add a single object to a group, and the group panel when we want to add multiple.