I have discovered this bug long ago, but Liam was on other planet - so i did not post it:)
If you go - WT\Options\DISM - then add new dism file (v10 for example) you will get a message "there is nothing to undo".
Also if u cannot repeat this bug then try this: WT\Options\DISM - then add new dism file. After that remove new dism and try to add again - "there is nothing to undo" 100500%.
video link: http://www.mediafire.com/watch/1v6br90gdbxz4cw/DISM_bug.mp4