On the main page I have a table with links corresponding to records in db. When the link is clicked popup window opens and user may edit content of the form (db record) and click Save or Close buttons. At the same time programming lock is applied on the db record preventing others from modifying the same record. Clicking Save/Close causes post of the form with hidden input 'action' set to 'Save' or 'Close'. In both cases pop-up is closed. Unfortunately if the user clicks on X in window decoration, application does not know about it (and record in db remains locked). Is there any clever way of either preventing user clicking X or more elegantly somehow informing server program of what had happened.

Could anybody offer a hint how to solve this problem?

I'm pretty sure that php isn't the tool you're looking for in this case. I think javascript is the way to go. Unfortunately I'm no pro at javascript so I can't help you there. Try posting the javascript forum

I just realized there is no javascript forum. Try the DHTML forum or the "Coding-All the Rest" forum. They can probably help you.