thunderbird colors broken by upgrade from 38.8 to 45.2

[Jason Paul Joines]

         I'm using Kubuntu 14.04.4 and Thunderbird suddenly became 
almost unusable yesterday because of a change in the color scheme.  From 
dpkg.log, this seems to be the culprit:

2016-07-25 11:26:49 upgrade thunderbird:amd64 
1:38.8.0+build1-0ubuntu0.14.04.1 1:45.2.0+build1-0ubuntu0.14.04.3

         It seems to be ignoring my system color scheme, and to be the 
only application doing so.  Even Firefox 47.0 is still cooperating.  In 
Thunderbird, there is no longer a color distinction between the selected 
message and unselected messages in the message list.  If I select text, 
such as an email address or subject or something in the message body, 
both selected text and selected text background are black, so I cannot 
see the selected text.  In the addressing area of a message, there is no 
distinction between one address line and the next, so it just looks like 
one big area.

         I've tried to downgrade to 38.8 via "apt-get install" but it 
seems 38.8 is no longer in the repository.  "apt-cache show thunderbird" 
shows only versions 45.2 and 24.4.

         Any ideas how I can fix Thunderbird 45.2 or downgrade to 
Thunderbird 38.8?


Thanks,

Jason
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