Many thanks for the update.
I have just tried the new 'per account' colour chooser, but it only seems to change the background of the title tab in the Accounts List, not the background of the actual items in the Messages List and/or the Inbox/Sent messages lists.
I would find that colour option extremely useful if it changed the background colour in the Messages List (and in the Widget view too) as that would be much more effective and useful than the little colour indicators in the corners of messages - and it would take up less screen space too. Could you maybe add a simple tickbox in the new Assign Colour screen to make that colour apply to Message List item backgrounds too? Thanks!
Andre