Thank you for your post.
This issue occurs with FileMaker Pro 12 and FileMaker Pro 13 under Mac OS X 10.8, 10.9 and 10.10. At this time, FileMaker Pro will not override the operating system behavior. I recommend submitting this as a suggestion to our Feature Requests web form at:
All entries into this web form populate a database file that is hosted and monitored by Product Management and Development. All entries are read, discussed and considered for possible implementation in a future release. Although I could copy your post and paste it into the web form, there are a couple of questions asked on the form that only you can answer.
So is there any work around available at this time? This seems a pretty series issue in certain particular cases.
One one hand, this is the expected behavior (OS, not FileMaker), finder window closes when option is pressed _while_ double-clicking on an object inside that window. One has to double-click AND THEN pressing alt
A real problem is, that FM becomes not the active app when starting by double clicking a file, one has to choose another app that is running, then back to FM. This problem appears in some postings here.
** Sorry for typing mistakes - but it's impossible to edit postings on iPad here
An entry in the Known Bugs List has been linked to this Issue Report. Any Comments/Questions/Suggested Corrections should be posted here or in a new thread. Please do not post such comments to the Known Bugs List thread.
This is not a fix, but a second workaround:
On my workstation, if instead of double-clicking the file, I drag it on the FileMaker icon of your dock (assuming you keep the application icon in your dock) while holding the option key at the same time, it gives me the login dialog without closing the Finder window where the file is located.
hope this helps,