In this context, you mean masking to hide parts of the map from player? The crosshatching effect on my maps (which can be changed to all sorts of different styles) is created using a mask, so I just wanted to clarify.
If that's what you're going for, there isn't a super obvious way to do it in my software yet, but after making your map, you could add a new layer, switch to the Hatching Tool, choose solid black hatching, or any other solid image and draw over any parts you want to hide. Then to uncover it, just use the erase tool with all but the hatching checkbox selected, and it'll unveil the parts of your map underneath.
If you were thinking of something else, let me know and I'll answer as best I can!
If that's what you're going for, there isn't a super obvious way to do it in my software yet, but after making your map, you could add a new layer, switch to the Hatching Tool, choose solid black hatching, or any other solid image and draw over any parts you want to hide. Then to uncover it, just use the erase tool with all but the hatching checkbox selected, and it'll unveil the parts of your map underneath.
If you were thinking of something else, let me know and I'll answer as best I can!