"...the problem with using "other" is that two or more different users would use the "other" value for two or more different values and that makes the replace field contents function useless when a lot of "other" values have been entered by different users for different values."
You might post a step by step example with real values to illustrate why/how this isn't working for you. I can't quite picture why you need to use replace field contents in this situation and there may be a way to do what you need without the extra development effort required to support your pop-up windows.
If you are using filemaker 10, you can use a script trigger (onObjectModify) to check for the greek letters in your check box field and then use Custom Dialog or a new window to ask for more information--but I wouldn't take on that extra work until I'm sure there isn't a simpler approach that works.
this is the process me and my tech support team currently go through on FM Pro 10:
1. Create new record
2. go to field "failure_category"(type of entry - drop-down menu, value list - Failure Category, no edit) and choose value that most closely resembles a failure that one of our customers reported.
3. if reported customer failure is not on the list, tech support person will choose "other" value.
4. I go through all records that contain "other" value and ask tech support team what the "other" value signifies.
5. tech support team tells me that "other" signifies "xxx" value.
6. I add "xxx" to the value list(Failure Category) and do a replace field contents calculation:
Case (failure_category = "other" ; "xxx") or If (failure_category = "other" ; "xxx")
The problem is that most of the time they do not communicate what each other are using the "other" value to signify, and that makes the replace field contents step useless.
Do you permit people to select multiple failure categories or just one per record?
A simpler approach might be to store all the values for this list in a separate table. Your "other" option can then be a button that displays this table in a different layout or uses new window to pop up it up in small floating window where users can add the "other" value to the table. Once they've added the new value in a new record in this table, it will automatically be added to your value list.
You can flag such entries with a second field in the table that identifies all newly added values so that you can review them for possible midification if you want.