Try watching a floating point variable. Then try to change its value to -1.0. The error message is "Operator '-' undefined for given types"
I can reproduce this - works in VS2010, but not VS2012 or VS2013. I will report it - thanks. Issue ID is DPD200253606.
I don't know if this is a record, but the developers told me that they just fixed this bug - I expect the fix to appear in Update 3.
Thanks Intel (Steve). This forum rocks.