x11-libs/fltk-1.1.7 continues emerging despite of previous errors.
Well, then post the emerge output, emerge --info and reopen then; we can't guess.
Created attachment 104764 [details] Emerge log (I pressed Ctrl+C.)
I know, I didn't manage.
Try the patch attached to Bug 136489 *** This bug has been marked as a duplicate of 136489 ***
The point is that emerging should be stopped when there were errors.
Created attachment 104767 [details] Emerge log with enforced errors (With option "-b" to show files.)
We really need just one bug to handle this issue; please take it there. *** This bug has been marked as a duplicate of 136489 ***
But could you explain why emerge doesn't stop?