bug#19576: write-file writes the wrong buffer

[martin rudalics]

> Martin, is there any reason why window_resize_apply doesn't set the
> frame's window_sizes_changed flag, but instead relies on its callers
> to do that?

No particular reason.  But note that ‘delete-other-windows-internal’ may
bypass window_resize_apply, so in that particular case we have to
manually make sure that the window_sizes_changed flag gets set.  I hope
this is the only case where it matters.

martin