Checking if your kit is complete...
Looks good
Writing Makefile for Tk::EntryCheck
cp lib/Tk/EntryCheck.pm blib/lib/Tk/EntryCheck.pm
Manifying blib/man3/Tk::EntryCheck.3
PERL_DL_NONLAZY=1 /home/cpanrun/build/5.6.1/bin/perl -Iblib/arch -Iblib/lib -I/home/cpanrun/build/5.6.1/lib/5.6.1/i686-linux-thread-multi -I/home/cpanrun/build/5.6.1/lib/5.6.1 -e 'use Test::Harness qw(&runtests $verbose); $verbose=1; runtests @ARGV;' t/*.t
t/Tk-EntryCheck.....1..1

One window will pop up now...

The following line will produce a warning...
EntryCheck: content of textvariabe too long at t/Tk-EntryCheck.t line 47

The following line will produce a warning...
EntryCheck: invalid chars by textvariable at t/Tk-EntryCheck.t line 53

Result:  ok ok ok ok ok

ok 1
ok
All tests successful.
Files=1, Tests=1,  4 wallclock secs ( 0.85 cusr +  0.02 csys =  0.87 CPU)
Installing /home/cpanrun/build/5.6.1/lib/site_perl/5.6.1/Tk/EntryCheck.pm
Installing /home/cpanrun/build/5.6.1/man/man3/Tk::EntryCheck.3
Appending installation info to /home/cpanrun/build/5.6.1/lib/5.6.1/i686-linux-thread-multi/perllocal.pod