On 5/2/06, Jerry James <james(a)xemacs.org&gt; wrote: the only thing i know of that might help is `annotations', i.e. marginal extents. these are designed for exactly this sort of thing (although they won't exactly overlay the text).

"Stephen J. Turnbull" <stephen(a)xemacs.org&gt; wrote: What, I wasn't specific enough? :-) I didn't know what bits of information myself; I just saw the uses of overlay-arrow-variable-list in the code. Further digging shows that the Emacs GDB support is still only using a single overlay arrow per debug buffer. The trick is that overlay-arrow-position and overlay-arrow-string can be used by only 1 buffer at a time. With the new Emacs stuff, they can support having multiple debug sessions going simultaneously, with an overlay arrow in each. A grep through the Emacs sources show that overlay-arrow-variable-list is used only by the gud/gdb-ui modes, and by simple.el to support next-error in compilation buffers. The Emacs approach means that minor modes can safely use overlay arrows, though, if anyone ever comes up with a minor mode that can meaningfully use one. As I see it, I have at least the following choices when porting the newer debugger interfaces: 1) Replace overlay-arrow-variable-list with the existing overlay-arrow-position/string and tell our users not to try to have multiple debugger sessions going simultaneously. 1a) Add overlay-arrow-variable-list to 21.5 and make the debugger Lisp detect and use it when available. 2) Take Ben's suggestion and check out the annotation package to see if it provides the needed functionality. 3) See whether any existing extent properties make them suffice for the purposes of the debugger code. -- Jerry James, Assistant Professor james(a)xemacs.org Computer Science Department http://www.cs.usu.edu/~jerry/ Utah State University