If run on a separate window, everything is fine. It's just when I click on the arrow to expand it from its default position that becomes unusable. I have to select the option to run it on a separate window to "recover" the control.
I believe that a savegame is not needed as it happens as soon as the game opens ANY scenario, but I'm attaching one anyway, and a screenshot of the effect after trying to use the log window...
Save:

This is happening with 1307.12 and 1307.13.
Cheers!