Seems the GNU screen project itself inserts leadings zeros into the version numbers reported. Probably to avoid confusion between version numbers like x.11 and x.2 - which one is newer then? x.11 could be the next version after x.10 or just a minor version number bump from x.1 and older than x.2.
Have you actually tried to use this feature?
For me adding mousetrack on
to my ~/.screenrc
changed behavior for Ctrl-A : windowlist
. With it I could move the selection of the window with my mouse, without the mouse had no effect. Did no further experiments with it, though.
I did this with Debian Jessie, exactly the same version of screen you have and Konsole as terminal. Might work different for other terminals, though.