A bit of confusion came my way when I was working on the map board of my module. Like many map boards, mine was superimposed with a hex grid. With the help of Inkscape and Gimp I was able to get my photo (jpg file) to the exact scale needed to coordinate with the hex tile pieces that will fit in the grid. Once I had scaled and manipulated the image in Gimp and saved it as a png file, it was easy to match up a hex grid on the image in VASSAL.
An odd thing about my map board is that each hex (37 total) is named for the city or town featured in the hex rather than a grid numbering system. So I decided to try out the Multi-zoned grid with a hex grid for the board to snap the tiles into place. I had determined to make 37 hex shaped zones, one for each hex and with the name of the city or town.
My confusion arose when I applied a hex grid to the board and also the multi-zoned grid to the board. When I saved the module I got an error message about having more than one grid for the board. I saved anyway, but although tile placements in the zones I had named (I started with just a few zones to see how it would turn out.) reported in the log as I wanted, none of the tiles would snap to any of the hexes like there was no grid. I tried again, but with only the hex grid, and the tiles snapped into place like I wanted. I reread the documentation on the hex grid and multi-zoned grid, but couldn’t figure out why the two grids didn’t seem to work together.
I noticed something in the documentation about adding a hex grid to a zone. It said the X and Y offsets applied to the board and not the boundaries of the zone. So after adding a zone to the Multi-zoned grid, I added a hex grid. I thought I was adding it to the zone, but the VASSAL tree structure made it look like the hex grid was added to the Multi-zoned grid. I used the same offsets I recorded when I got the VASSAL hex grid lined up with the one on the map image. Anyway, I checked the Use board’s grid box in the zone properties, and I got the reporting and snapping I wanted. As I added other zones, I checked the Use board’s grid box for each zone rather than adding another grid. It’s working great.
So I guess with Multi-zoned grid boards the proper way to add a hex or rectangular grid to the same board is to add it to the Multi-zoned grid. Anyway I hope this is helpful to other newbies.