bug#38181: Actual height of mode-line not taken into account

[martin rudalics]

> I simply don't yet understand why updating the frame decorations that
> have nothing to do with text layout needs init_iterator to run.  What
> am I missing?  Redisplay doesn't in general redraw the whole frame, it
> only redraws windows.

I don't understand either.  Fact is, that init_iterator is the only
agent within redisplay that frees realized faces and causes the new
border face to be realized.

martin