In a Microsoft Windows application, the KeyDown
event of a Simple style combo box is raised two times when you
press the PAGE UP, PAGE DOWN, UP ARROW, or DOWN ARROW key. This problem occurs
if the following conditions are true for the computer where the application is
- The Microsoft .NET Framework 1.0 is installed.
- The Microsoft .NET Framework 1.0 Service Pack 2 (SP2) is
- Hotfix KB812104 is installed.
To resolve this problem, obtain the latest service pack for
the Microsoft .NET Framework 1.0. To download the latest service pack, visit
the following Microsoft Web site:
has confirmed that this is a problem in the Microsoft products that are listed
in the "Applies to" section. This problem was
first corrected in the Microsoft .NET Framework 1.0 Service Pack
Steps to reproduce the behavior
- Start Microsoft Visual Studio .NET.
- On the File menu, point to
New, and then click Project. The New
Project dialog box appears.
- Under Project Types, click Visual
- Under Templates, click Windows
Application, and then click OK. By default, a form
that is named Form1 is created.
- Add a ComboBox control to the Form1 form. By default, the ComboBox1 combo box is added to the Form1 form.
- Right-click ComboBox1, and then click
Properties. The Properties window appears.
- In the Properties window, set the DropDownStyle property to Simple.
- In Solution Explorer, right-click the
Form1.vb file, and then click View
- Paste the following code before the End Class statement in the code window of the Form1.vb file.
Private Sub ComboBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles ComboBox1.KeyDown
- On the Build menu, click Build
- On the Debug menu, click
Start. Form1 appears.
- Select ComboBox1, and then press PAGE UP.
You will notice the behavior that is mentioned in the "Symptoms"
The message box appears two times. This behavior indicates that
event is raised two times.
For additional information, click the
following article number to view the article in the Microsoft Knowledge Base:
Description of the standard terminology that is used to describe Microsoft software updates