DO11: Three-button loses initial button definition

In v10, if you had a standard toolbar button, then customized it to turn it into a three-button button the previous button definition became the first (LMB) of the three-buttons.

In v11, turning a standard button into a three-button button causes the previous standard button definition to be lost... i.e. it's not added as the initial three-button.

Further, if you then deselect the three-button state for the top level button, the check mark next to the 'Three Buttons' item on the RMB menu goes away, but you're then left with an empty / buttonless three-button.

Tying up loose ends: That should be fixed in the newer betas.

Yep, confirmed fixed.