To fix the Color Picker of TextMate 2 under OS X Mavericks (10.9), do the following: open
~/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb, near lines 74-75 replace “AppleScript Runner” with “System Events”. That’s it.
If you want to edit the file in TextMate itself, use the following command:
mate "/Users/-your-username-/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb"
(For some reason ~ does not expand correctly to the path to my home folder).
Kudos goes to Jesse Burgheimer, who found the initial workaround and posted it on GitHub in the issue tracker of CSS Bundle.