Visual Basic Code of the Week (COTW)
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Issue #2
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Requirements for this Issue

The source code in this issue is designed for Visual Basic 3.0 and higher. The sample executables are available in 16-bit and 32-bit versions. The code will work in 16-bit or 32-bit versions of Visual Basic.

In this Issue

We are going to discuss a windows feature called "Always On Top." You have seen this feature used in toolbars and rollup menus to ensure they are always available to your application. The Windows Help system has this feature to allow you to keep a help window above your application window so you can follow the steps shown in the help pages.

AlwaysOnTop Subroutine

This subroutine will turn on and off the Always On Top flag for the form that is passed as a parameter.

Syntax

AlwaysOnTop(Form as Form, OnTop as Boolean)

Parameters

Form - The form object of the window you want to set the Always On Top option on or off.
OnTop - The flag determines the setting of the Always On Top flag. If set to true the form passed as Form will have the Always On Top option turned on. If false it will be off.

Sample Call

 
AlwaysOnTop(frmToolbar, True)
This call will turn on the Always On Top feature of the form called frmToolbar.

Source Code

To use this source code, just paste it into a module in your project and call the AlwaysOnTop subroutine from within your application.

' The SetWindowPos API call is the trick to getting the
' always on top feature to turn on and off.
#If Win16 Then
    Declare Sub SetWindowPos Lib "User" (ByVal hWnd As Integer, ByVal hWndInsertAfter As Integer, ByVal X As Integer, ByVal Y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer)
#Else
    Declare Function SetWindowPos Lib "user32" (ByVal hWnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
#End If

' Set some constant values for SetWindowPos (from WINAPI.TXT).
Public Const SWP_NOACTIVATE = &H10
Public Const SWP_SHOWWINDOW = &H40
Public Const HWND_NOTOPMOST = -2
Public Const HWND_TOPMOST = -1

Public Sub AlwaysOnTop(frm As Form, bOnTop As Boolean)
    ' Turn on the TopMost attribute.
    '
    ' Also passes the current position and size
    ' in Pixels.  Since window coordinates in
    ' VB are usually Twips we do a division to
    ' determine the correct number of pixels.
    If bOnTop Then
        lFlag = HWND_TOPMOST
    Else
        lFlag = HWND_NOTOPMOST
    End If
    SetWindowPos frm.hWnd, lFlag, _
        frm.Left / Screen.TwipsPerPixelX, _
        frm.Top / Screen.TwipsPerPixelY, _
        frm.Width / Screen.TwipsPerPixelX, _
        frm.Height / Screen.TwipsPerPixelY, _
        SWP_NOACTIVATE Or SWP_SHOWWINDOW
End Sub

Summary

That concludes this issue of COTW. We hope you find the source code useful in your development.

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