ACC2000: Example Using a Callback Procedure with Balloons

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This article applies to a Microsoft Access database (.mdb) and to a Microsoft Access project (.adp).

This article shows you how to use the Callback property of a Balloon object to determine which check boxes a user selected, or which label or button a user clicked, and then to respond to that selection.

NOTE: This article explains a technique demonstrated in the samplefile, FrmSmp00.mdb. For information about how to obtain this sample file,please see the following article in the Microsoft Knowledge Base:
233324 ACC2000: Microsoft Access 2000 Sample Forms Database Available in Download Center
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.
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A balloon is the area in which the Microsoft Office Assistant displaysheadings and text, similar to a message box. In addition to headings andtext, a balloon may contain other types of controls, such as check boxes,buttons, and labels, which are similar to option buttons.

To determine which label or button a user clicked, or which check boxes auser selected in a balloon, you must create a Callback procedure and setthe Callback property of the balloon to the name of that procedure. A Callback procedure is a procedure that runs whenever a modeless balloon is displayed.

To display a balloon with multiple buttons, labels, and check boxes, followthese steps:
  1. Create a module and type the following line in the Declarationssection:
    Option Explicit					
  2. On the Tools menu, click References, and then click Microsoft Office 9.0 Object Library to add it as a reference. If you do not see it in the list, search your hard disk for the file, MSO9.DLL.
  3. Type the following procedure:
    Sub OpenBalloon()   Dim offBalloon As Office.Balloon   Set offBalloon = Application.Assistant.NewBalloon   With offBalloon      ' Show the Office Assistant.      .Parent.Visible = True            ' Set the heading and text of the balloon.      .Heading = "Welcome to the Microsoft Office 97 Assistant!"      .Text = "Click one or more of the check boxes below, and " _           & "also click either a label or a button."            ' Make the balloon modeless.      .Mode = msoModeModeless            ' Display the Back, Next, and Close Buttons.      ' To determine the constants for other buttons you can place      ' on a balloon, view the Microsoft Office 8.0 Object library      ' in the Object Browser.      .Button = msoButtonSetBackNextClose            ' Display two check boxes.      .Checkboxes(1).Text = "Checkbox 1"      .Checkboxes(2).Text = "Checkbox 2"            ' Display two labels.      .Labels(1).Text = "Label 1"      .Labels(2).Text = "Label 2"            ' Define which Callback procedure to run.      .Callback = "WhichButton"      .Show   End WithEnd Sub					
  4. The following is an example of a Callback procedure written to use with the procedure demonstrated above.

    Note that the Callback procedure accepts three arguments: bln, iBtn, and iPriv. All Callback procedures that you write for use with balloons must accept these three arguments. The first argument, bln, defines the Balloon object that called the procedure. The second argument, iBtn, defines the value of the button or label that the user clicked. By using the iBtn argument, you can determine which button or label the user clicked. The third argument, iPriv, defines the value that uniquely identifies the balloon that called the procedure. The difference between the bln and iPriv arguments is that a programmer can use the iPriv argument to uniquely identify which balloon called the procedure. This allows a programmer to write one Callback procedure to use with all balloons, rather than having to write a separate Callback procedure for each Balloon.
  5. Type the following procedure:
    Sub WhichButton(bln As Balloon, iBtn As Long, iPriv As Long)   Dim cBox As Office.BalloonCheckbox   bln.Close   For Each cBox In bln.Checkboxes      If cBox.Checked Then         MsgBox "Selected " & cBox.Item      End If   Next   Select Case iBtn      Case 1         MsgBox "Clicked Label 1"      Case 2         MsgBox "Clicked Label 2"      Case msoBalloonButtonBack         MsgBox "Clicked Back Button"      Case msoBalloonButtonClose         MsgBox "Clicked Close Button"      Case msoBalloonButtonNext         MsgBox "Clicked Next Button"   End SelectEnd Sub					
  6. To test these procedures, type the following line in the Immediate window, and then press ENTER:
    Note that the Microsoft Office Assistant is displayed with a new balloon that contains multiple check boxes, labels, and buttons.

    Click one or more of the check boxes and either a button or a label. Note that you receive message boxes indicating which check boxes you selected and which button or label you clicked.
For more information about the Callback property, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type Callback property in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

Article ID: 209887 - Last Review: 10/25/2013 23:28:00 - Revision: 3.0

Microsoft Access 2000 Standard Edition

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