Never realised this before, but setting the 'Turn On Dimensioning Keypoints' box in Home:Preferences overrides the normal Mstn Snaps.
In effect, the normal key point etc Snaps are not available... only the Building Keypoints.
Whilst this is useful, it would be good to provide a quick means to toggle the setting on/off in the Locks Dialog.
In the meantime, is there a key in?
