Hm thank you for your answere, but there is no option "-mthreads" that can be found under "Project build options->Compiler settings->other options"
Neither under "debug" nor under "release". I guess a new project should work fine with linux - i'm going to make a new one when I've time. So up to then, if someone has another idea - i'm happy about every comment
And by the way: thank you for the explanation of the -mthread option, where did you found this? Google wasn't so chatty when i search