Use of uninitialized value $titlerx in regexp compilation at /usr/lib/x86_64-linux-gnu/perl5/5.20/X11/GUITest.pm line 347.
Use of uninitialized value $titlerx in regexp compilation at /usr/lib/x86_64-linux-gnu/perl5/5.20/X11/GUITest.pm line 347.

... Repeated many more times ...

Use of uninitialized value $titlerx in regexp compilation at /usr/lib/x86_64-linux-gnu/perl5/5.20/X11/GUITest.pm line 347.
Use of uninitialized value in subroutine entry at /usr/lib/x86_64-linux-gnu/perl5/5.20/X11/GUITest.pm line 545.