very nice Rated 5 out of 5 stars

this is something i've thought about writing for a while. it would be close to perfect, given:1. i believe it's against convention to take up a panel in Options, and it's worse if there's no icon.2. it should be clear if Date or Received is used.3. imo, the Date Format pref could be added as a tab in Options->Display; the column name doesn't need its own tab.4. the panel/tab could be automatically selected in the Options window when clicking options in addons manager (it's possible programatically).5. you don't need a new custom column, but can instead use the same method to override an existing column, and let the user decide to which columns the date format should apply.

[followup:] all you do is use dateCol or receivedCol in addColumnHandler(). but you need to get the dates like this: _fetchDate: function(aMsgHdr, aName) { let date = aName == "dateCol" ? : aName == "receivedCol" ? aMsgHdr.getUint32Property("dateReceived") * 1000000 : null; return date; },

[followup2:] the 2 options panels *really* need to be combined into 1... also, i think there is a better way than listbox (grid?) to display the format symbols help box; the text should especially be copy/select enabled (readonly textbox?). then it would be perfect. ;) 4->5

This review is for a previous version of the add-on (1.0). 


Thanks for your input.
1. Yes, I've moved it into Options > Display in the latest code.
2. I've updated the add-on page.
3. Yes, I've moved it into Options > Display in the latest code.
4. I'll look into this.
5. That one thing I wanted to do, but couldn't figure out how. However, if people would like to create multiple date fields, each with their own formatting, then I'm open to that as well.
Follow-up #1
Thanks for the code. As of version 1.1 the date format is applied directly to the "Date" and/or "Received" columns, and the new custom column has been removed.