Hi 1ac0 and welcome to LinuxQuestions,
I believe you got pgadmin3-1.18.1-x86_64-2_slack from SlackOnly at
http://slackonly.com/pub/packages/14...stem/pgadmin3/
In the same directory where you got pgadmin3 there is another file that tells you all the dependencies that you need:
http://slackonly.com/pub/packages/14.1-x86_64/system/pgadmin3/pgadmin3-1.18.1-x86_64-1_slack.dep
which lists these dependencies:
libgnomecups
libgnomeprint
libgnomecanvas
libgnomeprintui
wxPython
postgresql
It is a BAD IDEA to mix dependencies from SlackOnly and alien and slacky and random other places...
you should remove wxGTK (you need wxPython, not wxGTK), then get all these other dependencies from SlackOnly.