Comment 4 for bug 448872

> One has to deselect the object and select it again to be able
> to observe the correct bounding box.

I had a closer look and this isn't quite true: you can keep the current selection and still trigger a redraw of the new bbox setting if you
a) use <F1> or click once on the select tool button in the vertical
   toolbox on the left.
or
b) just continue to work with your selection set - the next drag/rotate
   action will immediately update the display of the new bbox setting.

(tested with Inkscape 0.46+devel r22528 on OS X 10.5.8)