Thanks for the reply - your interest is appreciated! However, I've been unable to find the [Index Item Popup Menu] item in any ini file. I can find the quoted items in the drop-down menu when in the Labels area when OperaMail is running but that's all. Can you be more specific please as to which file I should be looking for? My OperaMail is installed for multiple users and I can find an index.ini file in Users\Peter\AppData\Local\OperaMail\OperaMail\mail but it has nothing like an [Index Item Popup Menu] section in its contents.
Can you describe what the extra item is intended to do, please. The right-click menu appears to apply on to an individual, selected, label.
As a check that we are talking about the same version/platform, from 'About Opera Mail', Version 1.0; Build 1040; Platform Win32; System Windows 7.