Silly question about build functions

I am trying to add key bindings to (almost) everything in my settings menu so I can bind them to my steam controller but I am a little confused as to what “Add to Selection” and “Move Supported Structures” actually does.

Both of them are modifier keys, they work while pressed. I think “Add to selection” allows to select multiple structures at the same time (for example, you want to select two random walls and stretch / move them at the same time - although for rooms you can also double click one wall and it will select all the walls from that room).

“Move supported structures” allows to move only the lower room without dragging the room on top at the same time, it unsticks them while you have it pressed so that using the move widget works only for the selected structure. It can also be used to move surfaces made out of blocks, since double clicking them will select them only for extrusion, not for moving the whole thing.

“The key combo by default is Shift + Shift for both meaning I’d have to hold both my shifts to perform this by default?”
Was the question I was going to ask but just realized that I use these all the time. Just its default binding is confusing when looking at it.
The “Move Supported Structures” modifier might be named a little oddly as I though it meant to move everything that my selection supports. Maybe “Move Selected Structure” or something along the lines. Then again could just be me.

That’s a side effect. Shift is a modifier key, like Alt or Ctrl. When creating keybind combos, you can use a modifier key plus a normal key, if you’ve run out of single keys. In this case, we wanted to use only Shift, but the combo won’t get registered until you press the second key, if the first one you pressed was a modifier key. The UI doesn’t have anything to account for this case so I’m afraid it will stay like that.

You don’t need to press both shifts, just one, it will get registered since you have to hold it while you click on the other structure or drag the move widget.

Yeah, the naming is unfortunate, although it might make sense for blocks.