Q183332: BUG: TreeView Expand Event Does Not Occur When Using ENTER Key

Article: Q183332
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0,5.0
Operating System(s): 
Keyword(s): kbcode kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

The Expand event of a TreeView control does not occur when the ENTER key is
pressed to expand a node. Although the node actually expands as expected, the
Expand event is not triggered.

CAUSE
=====

This problem only occurs when the mouse is used to collapse the node (either by
clicking the + sign or by double-clicking the node), then the ENTER key is
pressed to expand the node. If the ENTER key is used to both collapse and expand
the node, the problem does not occur.

RESOLUTION
==========

A workaround in Visual Basic 5.0 is to trap for the ENTER key in the KeyDown
event of the TreeView control and then call the Expand event. See the "Steps to
Reproduce Behavior" section below for an example. This workaround is possible
only for Visual Basic 5.0 because the TreeView control in Visual Basic 4.0 does
not allow you to capture the ENTER key in the KeyDown event of the TreeView
control.

For more information, please see the following article in the Microsoft Knowledge
Base:

  Q150200 BUG: TreeView Control Does Not Receive Key Events

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this bug and will post new
information here in the Microsoft Knowledge Base as it becomes available.


MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Start a new Standard EXE project in Visual Basic 5.0. Form1 is created by
  default.

2. On the Project menu, click Components, and select "Microsoft Windows Common
  Controls 5.0."

3. Place a TreeView control on Form1.

4. Copy and paste the following code to the Form1 module:

        Option Explicit

        Private Sub Form_Load()
           With TreeView1
              .LineStyle = tvwRootLines  ' Linestyle 1
              .Nodes.Add , , "r", "Root"
              .Nodes.Add "r", tvwChild, "c1", "Child"
           End With
        End Sub

        Private Sub TreeView1_Expand(ByVal Node As ComctlLib.Node)
           MsgBox "TreeView1_Expand"
        End Sub

5. Run the project.

6. Press the ENTER key to expand the Root node. Notice the message box appears
  indicating that the Expand event has occurred.

7. Use the mouse to collapse the Root tree by clicking the minus (-) symbol next
  to Root. (It is important to use the mouse because the problem occurs only
  when using the mouse to collapse the node.)

8. Press the ENTER key.

  RESULT: The message box does not appear because the Expand event does not
  occur.

Workaround
----------

Replace the code in the Form1 module with the following code:

     Option Explicit

     Private IsExpanded As Boolean

     Private Sub Form_Load()
        With TreeView1
           .LineStyle = tvwRootLines  ' Linestyle 1
           .Nodes.Add , , "r", "Root"
           .Nodes.Add "r", tvwChild, "c1", "Child"
        End With
     End Sub

     Private Sub TreeView1_Collapse(ByVal Node As ComctlLib.Node)
        IsExpanded = False
     End Sub

     Private Sub TreeView1_Expand(ByVal Node As ComctlLib.Node)
        If IsExpanded Then Exit Sub
        MsgBox "TreeView1_Expand"
        IsExpanded = True
     End Sub

     Private Sub TreeView1_KeyDown(KeyCode As Integer, Shift As Integer)
        If Not TreeView1.SelectedItem.Expanded Then Exit Sub
        If KeyCode = 13 Then TreeView1_Expand TreeView1.SelectedItem
     End Sub

When you run the project, the KeyDown event of the TreeView control determines if
the ENTER key was pressed. If the ENTER key was pressed, code in the KeyDown
event calls the Expand event of the TreeView control. The IsExpanded flag
variable is used so that the Expand event code is not executed more than once.

Additional query words:

======================================================================
Keywords          : kbcode kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500 kbVB400Search kbVB400
Version           : WINDOWS:4.0,5.0
Issue type        : kbbug
Solution Type     : kbpending

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