I guess the wildcard character (%) is not supported, but Edit|Find does offer an option for regular expressions. I don't experience the issues you are seeing on either WinXP or (Oracle) Linux. Do you have the Match Case option checked off in either Edit|Find or the drop-down list to the right of the Binoculars icon?
If nothing else, you might want to try the Edit|Incremental Find Forward/Backward features.
I can't see any option for regular expressions in Edit|Find (which looks to be the same as right-click Find/Highlight). Are you typing in the 'regexp_...' on the command line to the right of the binoculars? How did you get the 'in', 'like', 'between' to work?
I see there is a 'Starts With' option, which goes a little way into providing wildcard functionality.
I guess I somewhat misinterpreted your question. A filter should support SQL predicates having IN, LIKE, and so on, but I thought you were referring to the Find Text dialog. Ctrl-F displays that dialog for a SQL or PL/SQL code editor, or the Worksheet or Script Output. Find/Highlighting dialog only applies to the grids for Query Results or Object Viewer and does not offer an option for regular expressions.