-// return the row number that that the y coord is near the edge of, or
-// -1 if not near an edge
+// return the row number that that the y coord is near
+// the edge of, or -1 if not near an edge.
+// coords can only possibly be near an edge if
+// (a) the row/column is large enough to still allow for an "inner" area
+// that is _not_ nead the edge (i.e., if the height/width is smaller
+// than WXGRID_LABEL_EDGE_ZONE, coords are _never_ considered to be
+// near the edge).
+// and
+// (b) resizing rows/columns (the thing for which edge detection is
+// relevant at all) is enabled.