Q231689: BUG: Moving Controls on a Form Triggers Form_MouseMove Event

Article: Q231689
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbActivexEvents kbVBp kbVBp600bug kbGrpDSVB kbDSupport
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
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SYMPTOMS
========

When you move controls on a form and the cursor is over the form, the form's
MouseMove event gets triggered even if the cursor is not moving.

RESOLUTION
==========

In this scenario, if you need to place code in the form's MouseMove event and
want to be sure it runs only when the mouse is actually moving, you will need to
set a flag before moving any control on the form. Check the flag in the
MouseMove event before executing any code.

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
---------------------------

1. Start a new Standard EXE project. Form1 is created by default.

2. Add a PictureBox control (Picture1) to Form1.

3. Add a TextBox control (Text1) to Form1. Make it high enough to display
  multiple lines and set the Multiline property to True.

4. Place three CommandButtons on the form. Name them as below and set the
  captions accordingly:

  cmdMove       &Move
  cmdStart      &Start Log
  cmdStop       &End Log

5. Add the following code to the module of Form1:

  Option Explicit
  Dim iLog As Long

  Private Sub cmdMove_Click()
      Dim l As Integer, t As Integer
      l = Picture1.Left + Picture1.Width / 2
      t = Picture1.Top
      Picture1.Move l, t
  End Sub

  Private Sub cmdStart_Click()
      Text1.Text = ""
      iLog = 1
  End Sub

  Private Sub cmdStop_Click()
      iLog = 0
  End Sub

  Private Sub Form_Load()
      iLog = 0
  End Sub

  Private Sub Form_MouseMove(Button As Integer, Shift As Integer, _
     x As Single, y As Single)
      If iLog = 1 Then Text1.Text = Text1.Text & "Form " & x & _
         " " & y & " " & Date & vbCrLf
  End Sub

6. Save the project.

7. Press F5 to run the project.

8. Place the mouse over the form.

9. You can move Picture1 by using Alt+M.

10. You can start logging MouseMove events by using Alt+S.

11. Start logging and move Picture1. Every time you move the picture, a
  MouseMove event gets logged in the TextBox. Note that this only happens if
  the mouse is over the form.

Additional query words:

======================================================================
Keywords          : kbActivexEvents kbVBp kbVBp600bug kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : WINDOWS:6.0
Issue type        : kbbug
Solution Type     : kbpending

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