Question: We use a semitransparent grid layer (.mig file) to show 'hotspot' intensity in MapBasic (MapInfo). Because the grid is just a rectangle, this looks ugly. See for instance:
![Hotspot example](https://i.stack.imgur.com/kUQO4.png).

Now MapInfo allows grid cells to be invisible (NULL), which would result in round-like hotspot regions.  

But we would prefer to extend the grid. Of course we could just add extra rows and columns, but that would require a lot of extra memory. And it would still show a boundary at some zoom level.

Is it possible to infinitely extend a grid layer with a constant value?

Answer: 
I dived a bit more into it.

We use MIGrid.dll. I found one (old) [reference](http://georezo.net/jparis/mb_r/doc/migrid_MB_calls/GE_MB_calls.pdf "MIGrid MapBasic calls").

A grid is mapped to a rectangular region (GE\_GRID\_INFO stuct). Every cell has equal size. So I'm afraid it's just impossible with grids.

If anyone knows of a workable alternative, using MapInfo...
The grid is created on the extents of the thematic data (selection or table). Therefore you could add two points of dummy data (top left and bottom right) of the extents of the projection.