Bivariate scatterplot mapset handling and color preferences

[baharmon]

The wxGUI bivariate scatterplot tool works with maps with the same name, but in different mapsets. However, it does not when generating / exporting regression statistics. It will only generate statistics for the map in the mapset that comes first alphabetically, despite displaying a scatterplot for a different set of maps.

Mapset handling is also an issue for the r.scatterplot add-on. Here it is more serious. Maps of the same name, but in different mapsets only create scatterplots for the first mapset alphabetically.

r.scatterplot input=map@a,map@b,map@c output=scatterplot

Also, most preferences for the bivariate scatterplot tool save successfully, but the color for points does not. It always returns to the default blue.