Microsoft KB Archive/898609

= FIX: Unexpected behavior may occur when a Windows Forms application raises the UserPreferenceChanged event in the .NET Framework 1.1 with SP1 =

Article ID: 898609

Article Last Modified on 12/3/2007

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APPLIES TO


 * Microsoft .NET Framework 1.1
 * Microsoft .NET Framework 1.1 Service Pack 1

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SYMPTOMS
In the Microsoft .NET Framework 1.1 with Service Pack 1 (SP1), when a Windows Forms application raises the UserPreferenceChanged event, unexpected behavior may occur in the application. This problem occurs when the application spawns multiple user interface (UI) single-threaded apartment (STA) threads and when UI events are handled on the background threads.



CAUSE
This problem occurs because the UserPreferenceChanged event is a system event where callbacks come from different threads that may not be thread safe. When a UI component is being updated in the event handler for the UserPreferenceChanged event, the call must be made thread safe by marshaling. However, the UpDownBase control and the DateTimePicker control that are included with the Windows Forms control library do not perform the marshaling themselves.

Note To make the UserPreferenceChanged event handling thread safe for these controls, the appropriate event handler must be overridden and marshaled.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next .NET Framework 1.1 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
To apply this hotfix, you must have the .NET Framework 1.1 SP1 installed on the computer.

Restart requirement
You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version        Size       File name --  30-Apr-2005  04:20  1.1.4322.2320  2,056,192  System.windows.forms.dll



WORKAROUND
For the UpDownBase control, the UserPreferenceChanged event handler is currently declared as follows. SystemEvents.UserPreferenceChanged += new UserPreferenceChangedEventHandler(this.UserPreferenceChanged);

private void UserPreferenceChanged(object sender, UserPreferenceChangedEventArgs pref) { if (pref.Category == UserPreferenceCategory.Locale) {   UpdateEditText; } } Note This code calls a UpdateEditText virtual method. This virtual method can be overridden.

To make this code thread safe, make the following change to the UpdateEditText function. protected override void UpdateEditText { Invoke(new MethodInvoker(UpdateEditTextBase)); } private void UpdateEditTextBase { base.UpdateEditText; }



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
This hotfix resolves the problem that occurs when you use the UserPreferenceChanged event for the DateTimePicker control and for the MonthCalender control. To work around the problem that occurs when you use the UserPreferenceChanged event for the UpDownBase control, see the &quot;Workaround&quot; section.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional query words: UserPreferenceChanged, event, multiple threads

Keywords: kbhotfixserver kbqfe kbprb KB898609

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