Matthew,
Seems the only difference between this new one and the original is that NSPrincipalClass is changed from SlickEditApplication to NSApplication ... is that correct?
This file doesn't seem to make any difference for me. I put it into /Applications/SlickEdit2012.app/Contents/, logged out, logged back in. Fonts are still noticeably fuzzy-looking on the retina display.
If it's any consolation, Excel for Mac looks worse. Only the menu text is clear. All other text, including button labels, and also graphics, are all fuzzy. With SlickEdit, button and other labels, and text in list boxes, is clear. Toolbar button icons are fuzzy, but I hide all the toolbars anyway. :-)
John Hurst