Hi, just lost bunch of data (maybe they are buried somewhere in DB, or at least, we have DB backup :).
What happened:

• I just moved lot of issues by mass-moving them from one project to another.
• I have defined custom fields in source project. These custom fields were defined not for "all projects" but only for specific ones - in this case, (ticket) custom fields were enabled only for source project and (by my mistake) not for destination project
• I moved all issues by multiple edit feature.
• And voila, all custom fields disappeared in new (destination) project, because there were not enabled for that project
• So I enabled these custom fields also for the new (destination) projects, so now they are available, but data from these fields was lost. I didn't examined how exactly RM is behaving in this case - if values of custom fields were deleted or if they are buried somewhere in DB.
• Anyway I think that solution can be very easy - when moving issues from one project to another (or tracker, etc.), and when there are not defined all custom fields in destination project/tracker, there should be some very clear/bright warning, something like "Hey dude, you are moving tickets to project/tracker where not of all currently used custom fields are defined/available, so you loose some data!" ...and if possible, list of there custom fields.

This will warn user so he/she can fix it before loosing data, like me :)

Or any other ideas, how to handle this situation?
PS: I'm describing only mass-ticket-update scenario, probably the same will be valid for single ticket copy/move