Improved introduction to mode-line

[Heime]

I would like to introduce indicators in the same way that one can do with 
"global-mode-string".
The problem with "global-mode-string" is that its contents are introduced after 
the last entries 
in the mode-line (after the mode lighters).  Then very convenient to remove 
what had been inserted
by resetting "global-mode-string".

But, viewing "global-mode-string" is almost impossible with small screens.  
What con I do that can
be introduced at the beginning of the mode-line but then also easily removed?