> I have just pulled latest Emacs and used with -Q option:
 > `global-text-scale-adjust' which I have used last days upon first
 > startup.
 >
 > Before I have not observed that windows shrink by using `+' or `-'
 > within that command.

I asked in another thread before and repeat the question here: Per se,
'global-text-scale-adjust' should never resize frames.  You have to
customize 'global-text-scale-adjust-resizes-frames' to achieve that
effect.  Please tell me what precisely you did.  If you did not
customize that option, something must be wrong within face-remap.el of
which I'm not aware.

 > Configured using:
 >   'configure --with-x-toolkit=lucid --with-mailutils'

I faintly recall that setting size hints with lucid here was completely
broken a couple of years ago.  In the attached patch I tried to excise
some of the changes I made to fix that then.  I also added some tracing
information that should be dumped to a buffer called *foo*.  So please
try the patch and if it does not work (or things even get worse) post
the contents of *foo* here.

Thanks, martin