win 7 x64
Worked: 2.6x- 2.71
Short description of error
In normal case you can move nodes by LMB, RMB or by press B. In this blend file in my configuration setup, moving nodes is accidential.
Some time it moves by LMB other time RMB and another time at all. In default settings it works fine. Also in panel user preferences tooltips don't work if you are above some function.
Exact steps for others to reproduce the error
open blend file and try to move some of two nodes every time using LMB or RMB.