getCharNumAtPosition() and transformations

[Baron, Randy {PRG~Basel}]

hi-    I am using the getCharNumAtPosition() method from SVGOMTextContentElement.  The user clicks on some text on the SVG display, the program gets the element clicked on from the target of the event, uses the MouseEvent's getClientX() and getClientY() to pass the point to getCharNumAtPosition(). It works very well...up to a point.  I can get the index of a character at a given position in the string but if I zoom or pan or rotate the canvas,  getCharNumAtPosition returns either a -1 or, in some cases, a number corresponding to a kind of virtual character that would have been on that location if the original display were still showing.  Does anyone know if this is the intended behavior?  Is it possible to have it continue finding the actual character that is clicked on after a transformation?   -Randy