VERIFIED SOLUTION i

How to create a Mask in MapInfo Pro application

Product affected: MapInfo Pro™ application
Follow these steps to create mask in MapInfo Pro™ application:

1.  Download the MapBasic code from our LI360 Community here.
2.  Create a new table called mask.tab.
3.  Create a polygon for this table. To keep it simple you can create a square, a bit larger then the map window or you can make it as big or small as you need, as long as it suits your area of interest.
4.  Then make the mask.tab editable and under OBJECTS menu use SET TARGET. Then select the polygons from the table that you don't want to be covered by the mask and under the OBJECTS menu again use ERASE.
5.  Save the mask.tab, now you have a "mask' that you can set your style with. 
UPDATED:  March 22, 2018