Starting with Ver6, there is no distinction between full-width and half-width characters. In Ver5, full-width characters were counted as two characters when the start position of the return value was found, but from V6 onwards, both full-width and half-width characters are counted as one character.
 
Example)

If you want to search for "efg" in Ver5
var a = ::FindStr("abcahefg", "efg");

The starting position "5" is stored in a.

If you want to search for "efg" in Ver6
var a = ::FindStr("abcahefg", "efg");

The starting position "4" is stored in a.