Bug in mouse click on invisible extent with end-glyph

I'm using XEmacs 21.4.12 on MacOSX. I've marked an extent in the buffer invisible and applied an end-glyph to it: (defun harmonia-code-view-set-extent-visible-p (extent visiblep &optional ellipses) (set-extent-property extent 'invisible (not visiblep)) (set-extent-end-glyph extent (and (not visiblep) (if ellipses (make-glyph ellipses) (make-glyph "..."))))) When I then click on the glyph with the mouse, the cursor jumps to character position 0 in the buffer. I've tracked this down to event-closest-position() returning nil in default-mouse-track-set-point-in-window(). Event-closest-position() returns nil when its call to event_pixel_translation() (C code) tells it that the bufp argument is 0. That happens because pixel_to_glyph_translation() tells it that ret_bufp is 0. Beyond that is a really complicated function in redisplay.c. :) The window has a menu, no toolbar, is a single buffer, and shows a modeline. The glyph in question can be anywhere in the visible buffer and shows the same behavior. The invisible extent covered by this glyph has quite a bit of text in it, but the glyph is only 3 characters and resides all on one line. Ideas? Andy ----------- Andrew Begel Ph.D. Candidate Computer Science Division University of California, Berkeley