On Saturday 21 March 2015 12:33:50 pm rolf wrote:
> Hello Mike
>
> thanks for you quick response.
>
> > > When I try to install tdm it complaines that "tdm requieres libr0 which
> > > is not an install candidate" so the dependensies could not be resolved.
> > > What to do next?
> >
> > Do you have builddeps configured in your sources.list?
>
> No, I hadn'd.
>
> I give it a next try witn the builddeps enabled (I really didn't understand
> what the repo is good for - exept I have a longer time to wait) and now
> trinity was not deinstalled - but some other packages - for example gimp,
> freecad...
>
> So many thanks for your help
> Rolf

I use apt-get  and dselect for package management..one reason aptitude wanted 
to remove packages I did not want removed..sound kind of like your situation.

If you do not mind trying apt-get and seeing if it behaves more to you wants. 
I never figured out why apt-get & aptitude differ in this regard.
-- 
Peace,

Greg