In the episode information window, I have a custom field named DVD to store the information that the episode is on which DVD.

I found the following problem in Mac OSX version, with version number:

Save & Close is bound to Command + S in this window (it can be triggered both by clicking on the GUI button, or hitting Command + S). When an information is added to my DVD field, it gets only saved when I click on the GUI button, it does not get saved when Command + S is used to trigger the Save & Close action.