Thanks for the confirmation that rotation of iconbar buttons is currently impossible. The commit mentioning a "fix" so that complete text is displayed, it considered the current rotation (orientation). I suppose I too-hopefully misread its intent. Ah, BTW, that reported issue remains -- I'm seeing the last character getting truncated from button labels (the dev probably didn't consider, and text, a variety of fonts) and for Boldface fonts, quite a few characters are being truncated/hidden. MAYBE the issue only arises when a certain setting (or combination: left / right / center / relative / justify) is specified.
The patch I mentioned in earlier post, it refers to files that no longer exist (like "FbTk/Container.cc") so I'll have to hunt for apropriate places to insert the changes.
Apparently the result would be a new button exposed in the Configure}}Toolbar submenu, enabling toggling of "Always horiz button labels".
Hmm, maybe whoever wrote that didn't think it through ~~ toggling on-demand is sort of pointless, b/c in order to fit the horiz textlabels, need to select a theme that specifies wider (taller?) toolbar.