Gmail Labels at Last! Rated 5 out of 5 stars
The ability to display Gmail labels (and remove them by clicking) is the single most significant feature missing in the Thunderbird e-mail experience. This is a fantastic add-on! I wanted this feature so much I was thinking about trying to spend my next vacation trying to hack together an extension to do this (and I likely would have run out of time before doing so successfully). THANK YOU!!
A couple ideas/issues with the buttons:
1. Change the "Delete" button (or add a replacement button that sends the same Thunderbird command) so that it more accurately describes the action that it performs--removing the e-mail from the current folder (the current Gmail label). Perhaps call the button "Remove Label" (or just "Remove") and change the red X icon to something that doesn't imply deleting.
2. The "Trash" button initially displays as "Trash" with the icon, but then once I add it to the toolbar the text changes to "Error".
UPDATE: The "Trash" button appears to work if the "When I delete a message" option is set to "Move it to this folder: [Gmail]/Trash" but not if it is set to "Just mark it as deleted" or "Remove it immediately". Only the former setting causes Thunderbird 16 to display the Trash folder with the GUI trash icon. Perhaps you should configure the "Trash" button to Move to "[Gmail]/Trash" regardless of the Thunderbird setting for "When I delete a message".
UPDATE 2: After changing the setting to "Move it to this folder: [Gmail]/Trash" and then changing it back to "Just mark it as deleted", the "Trash" button still appears to work. So I'm not sure what caused the glitch.
Other UI Thoughts:
1. I know (think) that X-GM-LABELS does not return the label for the current folder, so it is excluded from the list of Gmail Labels displayed in the header. BUT, I think it would be nice to still see that label listed as a convenient way to see at a glance which labels are applied to the e-mail (without also having to look up at the tab to see "SUBJECT - Folder"). It would be even better if the current folder could be displayed with a unique UI feature (such as a different color).
2. It would be great if the Gmail Labels were clickable so that, as in the Gmail website, clicking on a label would open that folder.