Hi Michael, I suggested the visual feedback (perhaps highlighting problematic edges in red) to avoid complicated error messages, though if an command fails, it would be nice for the command pane (top left corner) to at least display "command failed" or "union failed" or some such instead of just disappearing.

As far as commands which sometimes do not require pressing "done" go, most recently I ran into a bit of frustration unioning complex solids which I had preselected. I eventually reworked the solids, but the bewildering bit is this: the union takes a long time, and the "done" button still responds to clicks, but does not appear to do anything-- then the command pane disappears and I assumed the union had succeeded. I only discovered that it hadn't after trying to do another boolean operation where one of the failed union pieces was hidden from view. I retried the union a few times before I realized it was not operator error in applying the union, but that my model was broken in some way.

Will