HOWTO: Add a Horizontal Scroll Bar to a Visual Basic ListBox

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0

SUMMARY

The normal ListBox that comes with Visual Basic for Windows does not have a horizontal scroll bar. This can be a problem when the item in a ListBox extends past the boundaries of the ListBox. To add a horizontal scroll bar to the control, you can call the Windows API SendMessage function with the LB_SETHORIZONTALEXTENT constant.

MORE INFORMATION

This message sets the width in pixels by which a ListBox can scroll horizontally. If the width of the ListBox is smaller than this value, a horizontal scroll bar will be added to allow horizontally scrolling items in the ListBox.

Step-by-Step Example

1. Create a new Standard EXE project in Visual Basic. Form1 is created by default.



2. Add a CommandButton and a ListBox to Form1.



3. Paste the following code into the general declaration section of Form1:

   
         Option Explicit
   
         Private Declare Function SendMessageByNum Lib "user32" _
           Alias "SendMessageA" (ByVal hwnd As Long, ByVal _
           wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
         Const LB_SETHORIZONTALEXTENT = &H194
   
         Private Sub Command1_Click()
            Dim s As String
            Static x As Long
            s = InputBox("Please enter any text", "List scroll", _
              "this is a simple scrollbar sample for demonstration purposes")
            List1.AddItem s
            If x < TextWidth(s & "  ") Then
               x = TextWidth(s & "  ")
              If ScaleMode = vbTwips Then _
                  x = x / Screen.TwipsPerPixelX  ' if twips change to pixels
              SendMessageByNum List1.hwnd, LB_SETHORIZONTALEXTENT, x, 0
            End If
         End Sub
    




4. Run the project and click on Command1. You will be prompted to enter a text string to be added to the ListBox. Each time you enter a string, the code checks to see if it is longer than the previous longest string and will adjust the scroll bar as necessary.

REFERENCES

For information on performing this task in 16-bit versions of Visual Basic, please see the following article in the Microsoft Knowledge Base:

Q80190 : HOWTO: Add a Horizontal Scroll Bar to Visual Basic ListBox

Additional query words: kbDSupport kbDSD kbVBp kbVBp400 kbVBp500 kbVBp600 kbCtrl kbAPI

Keywords : kbGrpVB
Version : WINDOWS:4.0,5.0,6.0
Platform : WINDOWS
Issue type : kbhowto