d.rast.num: Constrain rendering within the current display extent in …

…the wx monitor (#3489)

* d.rast.num: Use GRASS_REGION to constrain rendering within the current display extent

* Use -1 instead of < 0

* Use PR #3500

display/d.rast.num/main.c

@@ -137,6 +137,9 @@ int main(int argc, char **argv)
     if (G_parser(argc, argv))
         exit(EXIT_FAILURE);
 
+    /* Setup driver and check important information */
+    D_open_driver();
+
     map_name = opt.map->answer;
 
     if (strcmp("none", opt.grid_color->answer) == 0)
@@ -221,10 +224,6 @@ int main(int argc, char **argv)
                         "not allowed)"));
     }
 
-    /* Setup driver and check important information */
-
-    D_open_driver();
-
     if (opt.font->answer)
         D_font(opt.font->answer);
     else if (opt.path->answer)