blocks with [default] corners not placed properly in columns env
I came across an issue with blocks using the default (i.e. not rounded) corners. When such a block is placed inside a column, the whole column gets shifted to the left. The block does no longer properly align to a block outside of the columns env (see attached test case).
I believe that the strange behavior originates in the code for beamercolorbox in beamerbasecolor.sty:
When I change (around line 210)
(\vbox to \hbox), everything seems ok.
Do you believe that this fix is ok, or do I mess up anything else?