Like others have posted, seperate the executable, for it is useless for non-win32 users, yet it's 2.2M.
I would like to see more coloring, like variables, brackets, parens etc.
Also I'd like to note that the comments (gray) are barely readable due to the background. It'd be cool to be able to set the colors yourself. And I find the choice of red for print commands quite odd, but that's all personal preference. (I see red as an error)
When/if you implent the color preference choose dialog, please include an option to change the font size too, for I find it quite big.
I wondered why my scripts were "not recognized as a valid Perl script", when pressing the "Run Script!" button, but the source showed me that's because I (almost) never use a .pl extension. Why did you choose for such a test?