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Microsoft KB Archive/173773

From BetaArchive Wiki

Article ID: 173773

Article Last Modified on 7/1/2004



APPLIES TO

  • Microsoft Visual Basic 5.0 Control Creation Edition
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Learning Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic 6.0 Enterprise Edition
  • Microsoft Visual Basic 4.0 Standard Edition
  • Microsoft Visual Basic 4.0 Professional Edition
  • Microsoft Visual Basic 4.0 32-Bit Enterprise Edition



This article was previously published under Q173773

SUMMARY

This article demonstrates how to move a form with the mouse when the form has no title bar by using the 32-bit Windows API SendMessage function with the WM_NCLBUTTONDOWN message.

MORE INFORMATION

The WM_NCLBUTTON message is generated by Windows when a user right-clicks on a window's title bar. Windows uses this message to determine whether the window should be moved by further user actions. If the title bar does not exist, this message is not generated. However, it is often useful to move a window when it doesn't have a title bar. A window or form in 32-bit Visual Basic will not have a title bar under the following circumstances:

   Visual Basic 5.0 and Visual Basic 6.0
      Caption = ""
      ControlBox = False

   Visual Basic 4.0
      Caption = ""
      ControlBox = False
      MaxButton = False
      MinButton = False
                


The sample code below illustrates a way of letting users move a form without a title bar by simply clicking and dragging it from anywhere on the form. The code placed in the MouseMove event procedure of Form1 may be placed in other event procedures, if so desired. For example, the code could be placed in the MouseDown event procedure of a Label control allowing movement of the form by selecting and dragging from the Label control.

NOTE: In Visual Basic 4.0, a form with a menu will have the title bar supplied by default so the method demonstrated below is not necessary. In Visual Basic 5.0 and Visual Basic 6.0, a form with a menu will not have a title bar supplied by default.

Step-By-Step Example

  1. Start a new Standard EXE project. Form1 is added by default.
  2. Set Form1's ControlBox, MinButton, and MaxButton properties to False, and then clear its Caption.
  3. Place a CommandButton control (Command1) on Form1.
  4. Place the following code in the General Declarations section of Form1:

          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
    
          Private Declare Sub ReleaseCapture Lib "User32" ()
    
          Const WM_NCLBUTTONDOWN = &HA1
          Const HTCAPTION = 2
    
          Private Sub Form_Load()
             Command1.Caption = "Exit"
          End Sub
    
          Private Sub Form_MouseMove(Button As Integer, Shift As Integer, _
                                     X As Single, Y As Single)
             Dim lngReturnValue As Long
    
             If Button = 1 Then
                Call ReleaseCapture
                lngReturnValue = SendMessage(Form1.hWnd, WM_NCLBUTTONDOWN, _
                                             HTCAPTION, 0&)
             End If
          End Sub
    
          Private Sub Command1_Click()
             End
          End Sub
    
                            
  5. Press the F5 key to run the program. Clicking and holding over Form1 will allow you to move the form. Pressing the CommandButton control will exit the program.


REFERENCES

For information on how to move a form without a title bar in 16-bit versions of Visual Basic, please see the following article in the Microsoft Knowledge Base:

114593 : How To Move a Form that Has No Titlebar or Caption


Keywords: kbhowto kbapi kbnetwork KB173773