How to Activate a Window API to Show in VB6

When developing an application in Visual Basic 6, if you want to activate another Windows application or window, you can do so easily. If, however, you want to make that window appear to the front and be shown, it requires a lot more code that you may initially realize. This process is very useful as it allows you to interact with other programs on your computer. Note that you cannot use this process to launch another application that has been created in VB6.

Instructions

1. Open your VB6 script in your preferred VB editor.

2. Copy and paste the following code into the declarations code:
   Private Declare Function FindWindow Lib "user32" _
   Alias "FindWindowA" _
   (ByVal lpClassName As String, _
   ByVal lpWindowName As String) As Long

   Private Declare Function GetClassName Lib "user32" _
   Alias "GetClassNameA" _
   (ByVal hWnd As Long, _
   ByVal lpClassName As String, _
   ByVal nMaxCount As Long) As Long

3. Copy and paste the following code into the procedures section:
   Public Sub GetClassNameFromTitle()
   Dim sInput As String
   Dim hWnd As Long
   Dim lpClassName As String
   Dim nMaxCount As Long
   Dim lresult As Long
   ' pad the return buffer for GetClassName
   nMaxCount = 256
   lpClassName = Space(nMaxCount)
   ' Note: must be an exact match
   sInput = InputBox("Enter the exact window title:")
   ' No validation is done as this is a debug window utility
   hWnd = FindWindow(vbNullString, sInput)
   ' Get the class name of the window, again, no validation
   lresult = GetClassName(hWnd, lpClassName, nMaxCount)
   Debug.Print "Window: " & sInput
   Debug.Print "Class name: " & Left$(lpClassName, lresult)
   End Sub

4. Click "GetClassNameFromTitle" in the debug window and click "Run". This should display the class name of the window. This provides the basic structure for the process.

5. Add the following script if you want to include the process in a wrapper:
   Public Function fActivateWindowClass(psClassname As String) As Boolean
   Dim hWnd As Long
   hWnd = FindWindow(psClassname, vbNullString)
   If hWnd > 0 Then
   ' ShowWindow returns True if the window was previously hidden.
   ' I don't care so I use the sub style
   ' ShowWindow and SW_SHOW declared elsewhere
   ' SW_SHOW will display the window in its current size and position
   Call ShowWindow hWnd, SW_SHOW
   fActivateWindowClass = True
   Else
   ' FindWindow failed, return False
   fActivateWindowClass = False
   End If
   End Function

References

• Visual Basic 6: Activate Any Window WIth API