BUG: TreeView Nodeclick Differences with Mouse and Keyboard

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

SYMPTOMS

The SelectedItem property of the TreeView control is updated at different times depending on whether the selected node is changed with the mouse or keyboard.

WORKAROUND

Within the NodeClick event, take into account that the SelectedItem property may be different depending on the action that caused the NodeClick event. One method to workaround the specific problem mentioned above would be to create a private form-level variable and store a reference to the node each time the NodeClick event is fired. In the example above, this node can be compared to the Node object passed to the NodeClick event to determine whether or not the NodeClick is a result of clicking on a new node. After declaring the form-level variable with this code in the Declarations section

   Private LastNode as Node

   If LastNode = Node Then Exit Sub
   LastNode = Node

STATUS

Microsoft has confirmed this to be an issue in the Microsoft products listed at the beginning of this article. Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

When the current node of a TreeView control is touched using the mouse, the SelectedItem property is updated after the NodeClick event. When the node is modified by using the keyboard, SelectedItem is updated before the NodeClick. This makes it difficult to execute code based on the Node object because a different object will be passed to the NodeClick event depending on whether the mouse or keyboard was used to generate the NodeClick. For example, if the intent of the code in the NodeClick event should be fired only when a new node is clicked upon, the following line of code will work fine if the mouse is used, but will not work if a user changes the selected node with the keyboard:

   If Node = TreeView1.SelectedItem Then Exit Sub

Steps to Reproduce

1. Start Visual Basic 4.0, or, if it is already running, start a new project.

2. Add a single TreeView control to the form.

3. Add this code to the Form_Load event of Form1:

      Private Sub Form_Load()
         Dim nodX as Node
         Dim i As Integer
   
         For i = 1 To 10
            Set nodX = TreeView1.Nodes.Add(, , , "Node " & i)
         Next i
      End Sub
   
   

4. Add this code to the TreeView1_NodeClick event of the TreeView control:

      Private Sub TreeView1_NodeClick(ByVal Node As Node)
          If Node = TreeView1.SelectedItem Then
              Debug.Print "Clicked on same node"
          Else
              Debug.Print "Clicked on other node"
          End If
      End Sub
   
   

5. Press F5 to start the application. Click on Node 1 and see the string "Clicked on same node" in the debug window (as expected). Click on Node 2 and see "Clicked on other node" in the debug window (also as expected). Now use the down arrow key to move from Node 2 to Node 3. The output string seen in the debug window is "Clicked on same node."