DOCUMENT:Q183332  01-APR-1998  [vbwin]
TITLE   :BUG: TreeView Expand Event Does Not Occur When Using ENTER Key
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:4.0,5.0
OPER/SYS:WINDOWS
KEYWORDS:VBKBCtrl kbcode

======================================================================
---------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Standard, Professional, and Enterprise Editions,
   32-bit only, for Windows, version 4.0
 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   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:

   ARTICLE-ID: Q150200
   TITLE     : 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.

======================================================================
Keywords          : VBKBCtrl kbcode
Version           : WINDOWS:4.0,5.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbpending

=============================================================================

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