So it seems that the latest version of the RLV (before this one) introduced a new bug after a bug fix. Namely the "can't alt-right-click on an object to sit on it when in Mouselook, through a HUD prim". This had the unfortunate side-effect of not being able to left-click on any HUD while in Mouselook. D'oh.
So here is a new version with a bug fix for the bugged bug fix. *nods*
You can grab the RLV for Windows here :
Direct download :
And the MD5 hash for the executable is
Have fun and sorry for the inconvenience,