IDLE calltips cause application error

[kupuguy]

BPO	546078
Nosy	@gvanrossum, @tim-one, @kupuguy
Files	idle.txt: Patch to clamp the width of the calltip label

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/tim-one'
closed_at = <Date 2002-04-23.19:23:39.000>
created_at = <Date 2002-04-19.11:38:18.000>
labels = ['expert-IDLE']
title = 'IDLE calltips cause application error'
updated_at = <Date 2002-04-23.19:23:39.000>
user = 'https://github.com/kupuguy'

bugs.python.org fields:

activity = <Date 2002-04-23.19:23:39.000>
actor = 'hobbs'
assignee = 'tim.peters'
closed = True
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2002-04-19.11:38:18.000>
creator = 'duncanb'
dependencies = []
files = ['436']
hgrepos = []
issue_num = 546078
keywords = []
message_count = 12.0
messages = ['10421', '10422', '10423', '10424', '10425', '10426', '10427', '10428', '10429', '10430', '10431', '10432']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'tim.peters', 'nnorwitz', 'duncanb', 'hobbs']
pr_nums = []
priority = 'high'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue546078'
versions = []

[kupuguy]

I can reproduce this bug on Python 2.2 and Python 2.1
on different Windows 2000 machines.

Start a copy of IDLE.
At the interactive prompt type the following
interactive session:

>> s = "%"*3000
>> def f(p=s): pass

>> f(

Instead of showing a calltip window with the arguments
for f, idle dies with an application error dialog:

idle: pythonw.exe - Application Error
The instruction at "0x1000a01f" referenced memory
at "0x00000000". The memory could not be "read".

This happens whenever the calltip string gets too long
(somewhere between 2500 and 3000 characters).

[nnorwitz]

Logged In: YES
user_id=33168

I couldn't replicate this bug...well, not exactly.
On Linux (redhat 7.2), I tried the example and there was no
problem. I increased 3000 to 30,000 and still no problem.
I then changed % to * and my X server crashed!

So I think the problem you are seeing is Windows specific,
but there may be a Tk problem also.

[gvanrossum]

Logged In: YES
user_id=6380

I just tried this with Python 2.2.1 and cannot reproduce it
either, but then I'm on Win98 and don't have easy access to
Win2K. If this really is Win2K specific, TIm is our only
hope, so I've assigned to him. (Tim, all I need at this
point is to see whether you can reproduce this on Win2k.)

[tim-one]

Logged In: YES
user_id=31435

Guido, are you sure this works for you? It crashed for me
on Win98SE, using the distributed 2.2.1. It's an "illegal
operation" error, and it says

PYTHONW caused a general protection fault
in module DIBENG.DLL at 0005:00003f2f.

MS claims this is due to a bad display driver:

http://support.microsoft.com/directory/article.asp?ID=KB;EN-
US;Q235618

but I doubt that's really the cause here. I also doubt
we'll ever know the true cause: we're deep in the land of
undocumented MS DLLs without source code, and how they
interact with Tk's implementation.

Offhand I guess the problem would go away if CallTips.py
clamped the length of the string it tried to display.

[gvanrossum]

Logged In: YES
user_id=6380

Yes, I'm positive. I've typed it in exactly, and verified
that I'm using 2.2.1 #34.

Regardless, I think that clamping the length of the string
makes a lot of sense.

[tim-one]

Logged In: YES
user_id=31435

Boosted priority (it's crashing X servers too!).

[tim-one]

Logged In: YES
user_id=31435

Neal, can you try the attached patch in your Linux
scenario? Whether it works or not, assign this back to
me. It fixes my problem on Win98, so I'm going to check it
in regardless, but I'll leave the bug open.

[nnorwitz]

Logged In: YES
user_id=33168

Works for me.

[tim-one]

Logged In: YES
user_id=31435

Thank you, Neal! Closing as Fixed, despite that we'll
never know what it caused it <wink>. I'll verify on Win2K
tomorrow and reopen if it fails there (seems exceedingly
unlikely, though).