1 - Hide/Show Surrounding Area 
  

 video - tutorial
 

1. Select the polygon on the map and insert the polygon into "Poly 1" [ 1 ].
2. Open the Functions menu [ 2 ] and select [ 3 ] "Hide / Show surrounding area of polygon 1"
3. The surrounding is hidden / shown.

or using a transparent background:

All european countries - are available as hulls, each country as a polygon.

The following example shows the Baltic Countries "Finland, Sweden and Norway" cropped out from the MapPoint map :