I thought I had found a bug, but it happens in version 5, 5.5 & 6 so I'm convinced it must be a "feature".

Here is what happened. I was very carefully cleaning up a database that has way to many fields that are not being used. When I finished, I noticed that buttons have been removed from ALL the layouts in that file. Apparently Filemaker doesn't distinguish layout objects beyond their labels. If a button label matchs a field name, and the field is deleted (from the define fields dialog), so are all buttons that happen to match the name of the field that's being deleted!

Granted, this is helpful for removing fields from layouts, but I don't think it's appropriate to remove buttons also. Now I have to go back and replace / re-order the buttons.

Oh, my!

I tested this, and confirm that you've found a true bug. This needs to be reported to Filemaker, Inc. You could try . http://www.filemaker.com/company/product_feature_request.html

Changing the file name will also effect the labels.

Confirmed.

I almost never deleted field from my databases, so I couldn't find that bug

This feature exists since version 2. And it IS well known and documented. I find it very helpful when renaming fields, because buttons are renamed automativcally. The drawback - well you have seen for yourself.

What they should do, then, is allow a preference for renaming/deleting buttons automatically.