ADK/ADT: How to Create Pop-up, Context-Sensitive Help

• Microsoft Access Distribution Kit version 1.1
• Microsoft Access Developer's Toolkit version 2.0

SUMMARY

Advanced: Requires expert coding, interoperability, and multiuser skills.

One alternative to displaying your application's online Help system in a separate window is to display it in a small, shaded pop-up window within your application. To do so, you can use the Windows API WinHelp() function with its HELP_CONTEXTPOPUP argument. This article describes how to implement such a Help system.

This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Access Basic, please refer to the "Introduction to Programming" manual in Microsoft Access version 1.x, or the "Building Applications" manual in version 2.0.

This article also assumes that you are familiar with creating Windows Help files. For more information about creating Help files, refer to the "Help Compiler Guide" included with the Microsoft Access Distribution Kit version 1.1 and the Microsoft Access Developer's Toolkit version 2.0.

MORE INFORMATION

The Windows API WinHelp() function supports a large number of options. The HELP_CONTEXTPOPUP option opens a shaded pop-up window for you to display Help in. This window is similar to the window that opens when you click a glossary entry (green underlined text) in the Microsoft Access Help system.

To implement this feature you need to:

• Create a working Help system by setting the HelpContextID and HelpFile properties for your forms to a valid Windows Help file.
• Redirect the F1 key to call a user-defined function that opens the Help file using the HELP_CONTEXTPOPUP option.

The following steps describe how to create the user-defined function to open the pop-up Help window and how to redirect the F1 key.

NOTE: In the following sample code, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this code in Access Basic.

1. Open a new module and declare the Windows API WinHelp() and FindWindow() functions by entering the following lines in the module's Declarations section:

         Declare Function WinHelp% Lib "User" (ByVal hwnd%, ByVal _
         szHelpFile$, ByVal uCmd%, ByVal dwData&)
         Declare Function FindWindow% Lib "User" (ByVal szClass$, ByVal _
         szTitle As Any)
   

   NOTE: You may have some Microsoft Windows API functions defined in an existing Microsoft Access library; therefore, your declarations may be duplicates. If you receive a duplicate procedure name error message, remove or comment out the declarations statement in your code.

2. Enter the following line to add the constant for HELP_CONTEXTPOPUP:

         Const HELP_CONTEXTPOPUP = 8
   

3. Enter the following code in the module:

         Function Help ()
            Dim Cid As Integer, Dummy As Integer
            On Error Resume Next
            ' Get the HelpContextID of the active control.
            Cid = Screen.ActiveControl.HelpContextID
            ' The error is 2474 if no control is active.
            If Cid = 0 Then
               ' There is no control context ID, so check the form and get
               ' the HelpContextID of the active form.
               Cid = Screen.ActiveForm.HelpContextID
               ' The error is 2475 if no form is active.
            End If
            ' If there is a context ID, open the Help file with context.
            ' FindWindow() returns the handle of the Microsoft Access window.
            ' Specify your custom Help file for the second argument.
            If Cid > 0 And Cid < 32767 Then
               Dummy = WinHelp(FindWindow("OMain", 0&), "C:\Myhelp.Hlp", _
               HELP_CONTEXTPOPUP, Cid)
            End If
         End Function
   
   

4. Create the following new macro called AutoKeys to redirect the F1 key:

         Macro Name   Condition   Action
         --------------------------------
         {F1}                     RunCode
   
         AutoKeys Action
         ------------------------
         RunCode
            Function Name: Help()
   
   

REFERENCES

Microsoft Windows version 3.0 Software Development Kit "Reference Volume 1"