- if (hiddenColumn > region[0] && hiddenColumn < region[1])
- {
- return region[0] + hiddenColumn - result;
+
+ if (hiddenColumn >= region[0] && hiddenColumn <= region[1])
+ {
+ // Here the hidden column is within a region, so
+ // we want to return the position of region[0]-1, adjusted for any
+ // earlier hidden columns.
+ // Calculate the difference between the actual hidden col position
+ // and region[0]-1, and then subtract from result to convert result from
+ // the adjusted hiddenColumn value to the adjusted region[0]-1 value
+
+ return result - (hiddenColumn - region[0] + 1);