Thank you to all who so gentle answer me.
I sometimes build from source the software I want to install so I have a
little prectice with this kind of things.
For some reason It isn't always easy ( expecially where there are many
dependacies to solve).
But I think the using --prefix=/otherdirectory in the configure step I
can safely install two version of gimp.
I'd like to have two main version ( not the alpha or intermediate, at
least till I 'll be able to help with the debug or so).
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