Doah! (In my best Homer Simpson voice.) I did not realise that the yellow color meant it was active and the blue/gray meant it was inactive.

I was just clicking on the little tabs at the top of those buttons (checking and unchecking various function options). I did not see that rather IMPORTANT little fact mentioned in the documentation! ;>)

'm used to the standard Windows method of ghosting to indicate whether a control is active/available. Now, my snapping seems to be working as expected.

Thanks,

Johnny