I'm able to change values of variables in Perl Expressions View, but it it possible to see the results of statments like "print $background_color;" ? .... I just answered my own question trying this again, but here it is for anyone else who might run into thi: after you run your expression, in the "Debug" view window, click on "Perl Debugger" context and then the console will show the expression output, (and your codes STDOUT)
The execution of your expression seems to leave the console view attached to the debugger process interaction output. If you clicked on "Perl debugger" context to see the console, before running another expression you need to select your "Main Thread" process again.
hope that helps someone,
p.s. this is with EPIC 0.6.55, Eclipse Juno SR1, Perl 5.16.2