Thunderbird 154 changed the way interacting with the tray worked. Now when you click the 'X' to close the app, it will minimize to the tray instead of closing, assuming you have that option set. I understand this was a frequently requested feature. However, in adding that capability Thunderbird also removed the ability to minimize to tray using the minimize button, and that doesn't make any sense. This needs to be restored and be user configurable.
Changing the tray behavior like this fundamentally changes the semantic meaning of the Windows UI widgets when using Thunderbird. If I click the 'X', I expect the app to close. If I click the minimize button, I expect it to stay running without being displayed in a window on the screen (whether it minimizes to the systray or to the taskbar is a side discussion). This is how nearly all Windows apps have worked for decades. The changes in 154 have made it so that now when I click minimize it minimizes to the taskbar (not ideal since it's a regression in behavior, but doesn't affect windows semantics), but if I click the close box it now also minimizes the app, but to a different place. There is now no longer a way to close the app from the Windows UI widgets. I can optionally turn off the close to tray feature to restore being able to close the app, but that just shows the behavior regression when using the minimize control.
If you keep the close-to-tray option that people have been requesting, you also need to retain the minimize-to-tray option and have the feature configurable in the settings. For every person you please with close-to-tray, you've pissed off someone like me who now has to retrain years of muscle memory and has to selectively remember that Thunderbird no longer uses Windows UI widgets the same way as nearly every other Windows app does. This should never have been a mutually exclusive decision. Bring back the pre-154 behavior and make it user configurable.
