[sylpheed:36744] Issue with [Shift]-[Tab] when composing message

[Dennis Carr]

Running 3.7.0 on Linux under xfce, current version from Debian Stable. 

When composing a message, if I am in the body of the message then
[Shift]-[Tab] will simply insert a tab instead of moving back to the
Subject line.  This isn't really desired behavior and this behavior
only appears within Sylpheed while composing a message.  The desired
behavior is to move back to the previous field (Subject, in my case) in
a compose window.

How do I change this behavior?

-Dennis Carr