add buttons to solo frame

[atticus]

Here's a most basic question I failed to answer with the docs: how can you add further buttons to a Solo frame in a way, that still only one of those can be toggled on?
When I right-click on the frame to add another button in there or paste from clipboard, they behave as if they remain outside, so the function is added to the current instead of toggling the previous off when pressing the new one.

[SPS]

First you have to select the frame. Then if you add button, it will be in the frame.
You can check simple whether a button is in or outside the frame by moving the frame. The button must stay on his position within the frame.