BUG REPORT : Help Control 
Author Message
 BUG REPORT : Help Control

This is for everyone who wants to know, but especially for you guys up in
Redmond. I believe that I've found a bug in the Help Control while bullet
proofing a VBNet app that I'm currently authoring. Let's see if I can
explain it properly.

My app is a tabbed dialog that utilizes a TabControl, NotifyIcon, Timer,
Help, and a ContextMenu control, as well as the standard checkboxes and
buttons. The app is constantly enabling and disabling the timer control. It
constantly switches it's icons in the icon tray. It's constantly writing
text to a ListView control, all in the same window. The app is duration
driven so at a specified interval, different types of work takes place
thanks to the timer. I haven't incorporated ANY of the actual work part of
the app, ONLY the interface and it's functionality. In other words, if the
app is supposed to clear the screen, it doesn't do it yet, it just runs
through the process of getting to the point where it can do it. In most
cases I just display a message box like it did the work and move on. I wrote
it in this manner because the work part of the app is unmanaged code in a
C++ dll that I've also authored.

All right, here's the bug. Every control in the app utilizes the Help Button
in the app's title bar. If I click on the little title bar question mark and
then click on a control, a tooltip like help window pops up and display's
help for the control. If I go back and forth, clicking the title bar help
button and then clicking on the TabControl, eventually I'll get an error
message. I mean the way I'm doing it, no one ever would. I click the help
button, click the TabControl, click the help button, click the tab control,
all as fast as I can move the mouse. Within about 2 minutes I get the
following error message:

System.NullReferenceException: Object reference not set to an instance of an

I've included the app's error dialog text below if anyone is interested in
looking at it. Just to let you know, I originally wrote the app in C++ 6.0
and then in VB 6.0. Both versions work very well and have never displayed
this behavior. I wanted to write the thing in VBNet to see how well our new
platform performs. It could be that the timer is running a thread and the
help control ends up waiting for it, or, maybe it's the other way around.
Anyway, I thought that Thread Safe means Thread Safe. Maybe one of you guys
can figure it out or duplicate it if you have the time.


See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an
   at System.Windows.Forms.SafeNativeMethods.HtmlHelp(IntPtr hwndCaller,
String pszFile, Int32 uCommand, HH_POPUP dwData)
   at System.Windows.Forms.Help.ShowHTML10Help(Control parent, String url,
HelpNavigator command, Object param)
   at System.Windows.Forms.Help.ShowPopup(Control parent, String caption,
Point location)
   at System.Windows.Forms.HelpProvider.OnControlHelp(Object sender,
HelpEventArgs hevent)
   at System.Windows.Forms.Control.OnHelpRequested(HelpEventArgs hevent)
   at System.Windows.Forms.Control.WmHelp(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.TabControl.WndProc(Message& m)
   at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam)

************** Loaded Assemblies **************
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.209
    Assembly Version:
    Win32 Version:
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.0
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.0
    Assembly Version: 7.0.3300.0
    Win32 Version: 7.00.9466
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.0
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.0
    Assembly Version: 1.0.3300.0
    Win32 Version: 1.0.3705.0

************** JIT Debugging **************
To enable just in time (JIT) debugging, the config file for this
application or machine (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging

For example:

    <system.windows.forms jitDebugging="true" />

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT de{*filter*} registered on the machine
rather than being handled by this dialog.

BUG REPORT : Help Control

Mon, 31 Jan 2005 16:18:44 GMT  
 [ 1 post ] 

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