BUG: TreeView Node Tooltips Flash When Displayed from Modal Window (240924)

MORE INFORMATION

• Mscomctl.ocx is statically linked to version 5.x of Comctl32.dll, and is not affected by the version of Comctl32.dll installed on the target system.
  
  
• The workaround provided below is insufficient when running under Windows NT 4.0 and comctl32.dll version 4.x or lower is installed. In this case implement the workaround described in the Microsoft Knowledge Base article Q241097 referred to in the REFERENCES section below.

Steps to Reproduce Behavior

1. Start a new Visual Basic Standard EXE project. Form1 is created by default.
2. On the Project menu, select Components. Check either Microsoft Windows Common Controls 5.0 or Microsoft Windows Common Controls 6.0 and click OK.
3. Add two CommandButtons and a Label to Form1.
4. Add the following code to the General Declarations section of Form1:

   Option Explicit
   
   Private Sub Form_Load()
      On Error Resume Next
     
     ' Since the problem only occurs in the IDE, only disable the
     ' TreeView's Node tooltip window in the VB IDE.
     ' Since the Statement Debug.Print is removed by compiling, you can use
     ' it to throw an error to detect the IDE.
      Debug.Print 1 / 0
      If Err Then
         Command1.Enabled = False
         Command2.Enabled = False
         Me.Caption = "Application MUST be compiled"
      End If
      On Error GoTo 0
      Command1.Caption = "Show Form2 modally"
      Command2.Caption = "Show Form2 non-modally"
      Label1.Caption = "If Form2 is shown modally and run from a compiled " _
    & "executable, its TreeView Node tooltip window will repeatedly appear" _
    & " and disappear, unless you enable it (remove its WS_DISABLED)."
   
   End Sub
   
   Private Sub Command1_Click()
      If (Form2.Visible = False) Then
         Form2.Command1.Enabled = True
         Form2.Show vbModal
      End If
   End Sub
   
   Private Sub Command2_Click()
      Form2.Command1.Enabled = False
      Form2.Show
   End Sub
   					

5. On the Project menu, click Add Form to add a second form to the project.
6. Add the TreeView control and a CommandButton to Form2. Resize the TreeView Control so that 35 characters of Node Text are partially obscured.
7. Add the following code to the General Declarations section of Form2:

   Option Explicit
   
   Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
                             (ByVal hWnd As Long, ByVal wMsg As Long, _
                              ByVal wParam As Long, lParam As Any) As Long
   
   ' treeview messages
   Private Const TV_FIRST = &H1100
   Private Const TVM_GETTOOLTIPS = (TV_FIRST + 25)
   
   Private Const GWL_STYLE = (-16)
   Private Const WS_DISABLED = &H8000000
   
   Private Declare Function GetWindowLong Lib "user32" Alias _
    "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
   
   Private Declare Function EnableWindow Lib "user32" _
    (ByVal hWnd As Long, bEnable As Long) As Long
   
   Private Sub Form_Load()
      Dim i As Integer
   
      ' Fill up the treeview...
      For i = 1 To 10
         Call TreeView1.Nodes.Add(Text:="item" & i & String$(30, "x"))
      Next
      Command1.Caption = "Enable TreeView Tooltips"
   End Sub
   
   Private Sub Command1_Click()
      Dim hwndTT As Long
      Dim dwStyle As Long
     
     ' Get the handle of the TreeView's tooltip window
      hwndTT = SendMessage(TreeView1.hWnd, TVM_GETTOOLTIPS, 0, 0)
      If hwndTT Then ' If the tooltip window is disabled, enable it.
         If (GetWindowLong(hwndTT, GWL_STYLE) And WS_DISABLED) Then
            Call EnableWindow(hwndTT, 1)
         End If
      End If
   
     ' All done...
     Command1.Enabled = False
   End Sub
   					

8. From the File menu, choose Make Project1.exe.
9. Run the compiled executable and display Form2 both non-modally and modally, placing the cursor over TreeView Node text.
   
   NOTE: When displayed modally the tooltip window flashes unless the TreeView Node tooltip window is enabled by clicking the CommandButton.