See the image for the effect that results instead. This affects left, right and bottom positions.

With left/right you can get the bug by selecting icons or icons+labels and then switching to labels only.

With the bottom bar you get the pictured effect switching from icons to labels only. If you switch from icons+labels to labels only it almost works but there's a strange strip visible below the buttons (see picture toolbar2)

Source files involved: llui/lltoolbar and llui/llfloater