DOCUMENT:Q231465 28-MAR-2002 [vbwin] TITLE :BUG: WM_MOUSEWHEEL Message Ignored Adding UserControl to Form PRODUCT :Microsoft Visual Basic for Windows PROD/VER::5.0,6.0 OPER/SYS: KEYWORDS:kbMouse kbVBp kbVBp500bug kbVBp600bug kbWndwMsg kbGrpDSVB kbDSupport ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 - Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 - Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 ------------------------------------------------------------------------------- SYMPTOMS ======== After adding a User control to a Form, the Visual Basic design environment (IDE) ignores the WM_MOUSEWHEEL message when you roll the wheel of the mouse. This problem does not occur on Windows NT or Windows 2000. CAUSE ===== The Visual Basic Design Environment (IDE) is not compatible with early versions of the Microsoft Intellimouse driver. RESOLUTION ========== Download the latest driver update for the Microsoft Intellimouse from: http://www.microsoft.com/products/hardware/mouse/download.asp STATUS ====== Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. MORE INFORMATION ================ Steps to Reproduce Behavior --------------------------- WARNING: Failure to unhook a window before its imminent destruction may result in application errors, Invalid Page Faults, and data loss. This is due the fact that the new WindowProc function being pointed to no longer exists, but the window has not been notified of the change. Always unhook the sub-classed window upon unloading the sub-classed form or exiting the application. This is especially important while debugging an application that uses this technique within the Microsoft Visual Basic Development Environment (IDE). Pressing the End button or selecting End from the Run menu without unhooking may cause an Invalid Page Fault and close Microsoft Visual Basic. Changes to the active project will be lost. 1. Start a new Visual Basic Standard EXE project. Form1 is created by default. 2. Add the following code to the General Declaration section of Form1: Option Explicit Private Sub Form_Load() Me.Show Call SubClassHookForm End Sub Private Sub Form_Unload(Cancel As Integer) Call SubClassUnHookForm End Sub 3. On the Project menu, select the Add Module menu option. 4. Add the following code to the General Declaration section of Module1: Option Explicit Private MSWHEEL_ROLLMSG As Long Private m_PrevWndProc As Long Private Const GWL_WNDPROC = (-4) Private Declare Function CallWindowProc Lib "user32" Alias _ "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, _ ByVal msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long Private Declare Function SetWindowLong Lib "user32" Alias _ "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, _ ByVal dwNewLong As Long) As Long Private Declare Function RegisterWindowMessage Lib "user32" _ Alias "RegisterWindowMessageA" (ByVal lpString As String) As Long Public Sub SubClassHookForm() MSWHEEL_ROLLMSG = RegisterWindowMessage("MSWHEEL_ROLLMSG") ' On Windows NT 4.0, Windows 98, and Windows Me, change the above line to ' MSWHEEL_ROLLMSG = &H20A m_PrevWndProc = SetWindowLong(Form1.hwnd, GWL_WNDPROC, _ AddressOf WindowProc) End Sub Public Sub SubClassUnHookForm() Call SetWindowLong(Form1.hwnd, GWL_WNDPROC, m_PrevWndProc) End Sub Public Function WindowProc(ByVal hwnd As Long, ByVal msg As Long, _ ByVal wParam As Long, ByVal lParam As Long) As Long If msg = MSWHEEL_ROLLMSG Then Debug.Print "Receive MSWHEEL_ROLLMSG" End If WindowProc = CallWindowProc(m_PrevWndProc, hwnd, msg, wParam, lParam) End Function 5. Press the F5 key to run the program and roll the wheel button while the mouse pointer is positioned over Form1. 6. You will see "Receive MSWHEEL_ROLLMSG" displayed in the Immediate Window. 7. Stop the program. Do NOT use the END button on the toolbar per the warning note at the beginning of this section. 8. On the File menu, click Add Project... Select ActiveX Control in the Add Project dialog and click OK. UserControl1 is created by default. 9. Close the Project2 window and add a UserControl1 to Form1. 10. Press the F5 key to start the program and roll the wheel button while pointing the mouse on Form1. 11. The string "Receive MSWHEEL_ROLLMSG" no longer occurs in the Immediate Window. If you use Spy++ to detect all the Windows messages received by Form1, you will see that WM_MOUSEMOVE is received instead of WM_MOUSEWHEEL when you roll the wheel of the mouse after the UserControl is added. REFERENCES ========== For additional information, please click the article number below to view the article in the Microsoft Knowledge Base: Q168795 HOWTO: Hook Into a Window's Messages using AddressOf Additional query words: wm_mousewheel user control hook ====================================================================== Keywords : kbMouse kbVBp kbVBp500bug kbVBp600bug kbWndwMsg kbGrpDSVB kbDSupport Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 Version : :5.0,6.0 Issue type : kbbug Solution Type : kbpending ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.