Add message to Base point's 'Options' dialog why 'OK' is disabled

In this use case: 1. right click on Base Point (usually point A) 2. select 'Options' 3. change X and/or Y values the results are: 1. the OK button is grayed out, can only click 'Cancel'

To make this easier for user, make these changes for Base Point's 'Options' dialog: 1. Disable X & Y input fields 2. Display message "To move Base Point, right click on point and drag to new location'