bug#19966: 24.4; Get error on hover over variable for tooltip inspection, gud/pdb

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 27 Feb 2015 14:28:51 -0800
> From: Tom Burbage <tiburbage@gmail.com>
> 
> Using current binary build of Emacs 24.4 for Windows.
> emacs-24.4-bin-i686-pc-mingw32
> The use context is:
> 1 - Open a python source file
> 2 - M-x pdb  ;; run gud/pdb for the current .py
> 3 - step until a variable becomes defined/initialized
> 4 - hover the mouse over the variable name in the source
> The errors:
> Error running timer `tooltip-timeout': (wrong-type-argument markerp nil)
> Command: next [4 times]
> Error running timer `tooltip-timeout': (void-variable v) [2 times]

I cannot reproduce this.  Does this happen for you in "emacs -Q"?

Can you show a backtrace from these errors?

Are you sure you are using gud.el, gdb-mi.el, and tooltip.el from
Emacs 24.4, not shadowing any of them with different versions?

I tested this with "M-x gdb" debugging emacs.exe, not "M-x pdb"
debugging a Python program (don't have a setup for the latter).  Do
you see the same problem with "M-x gdb"?  If not, perhaps PDB behaves
differently when it gets the request for values sent by Emacs, please
try to look into that.

> - I have the tooltip.el tooltip-mode OFF/nil
> - I have gud-tooltip-mode ON (obviously)

A strange configuration, IMO, but I tried it is a well, and still
didn't see the problem.

> - If I start Emacs w/ --no-init, I can still reproduce the problem
> - If I replace progmodes/gud.el , gud.elc with those from 24.3, the
> errors do not occur
> 
> Other problems ensue on Windows when tooltip messages actually display
> as tooltip windows, and I suspect maybe it is an HWND stealing problem,
> but not sure and that's a different issue. I'm OK with the info being
> printed to the "echo area"

I don't see any problems with tooltips on Windows, neither in GUD nor
elsewhere.  What problems do you see?

Btw, even if I turn tooltip-mode OFF, and verify it's off by hovering
the mouse above tool-bar buttons, GUD tooltips still show as balloon
help for me.  Not sure if this is a bug or a feature, but it doesn't
seem to cause any harm here.