Set/Get the ShowInTaskbar property for a window at runtime

[manavo11]

'You need 2 command buttons 'cmdToggle' and 'cmdCheck'
 
Option Explicit
 
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
    (ByVal hwnd As Long, ByVal nIndex As Long) As Long
    
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
    (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
 
Private Declare Function ShowWindow Lib "user32" _
    (ByVal hwnd As Long, ByVal nCmdShow As Long) As Long
    
Private Const GWL_EXSTYLE = (-20)
Private Const WS_EX_APPWINDOW = &H40000
 
Const SW_HIDE = 0
Const SW_NORMAL = 1
 
Private Sub ShowInTheTaskbar(hwnd As Long, bShow As Boolean)
    Dim lStyle As Long
    
    ShowWindow hwnd, SW_HIDE
    
    lStyle = GetWindowLong(hwnd, GWL_EXSTYLE)
    
    If bShow = False Then
        If lStyle And WS_EX_APPWINDOW Then
            lStyle = lStyle - WS_EX_APPWINDOW
        End If
    Else
        lStyle = lStyle Or WS_EX_APPWINDOW
    End If
    
    SetWindowLong hwnd, GWL_EXSTYLE, lStyle
    
    App.TaskVisible = bShow
    
    ShowWindow hwnd, SW_NORMAL
End Sub
 
Private Function IsVisibleInTheTaskbar(hwnd As Long) As Boolean
    Dim lStyle As Long
    
    lStyle = GetWindowLong(hwnd, GWL_EXSTYLE)
    
    If lStyle And WS_EX_APPWINDOW Then
        IsVisibleInTheTaskbar = True
    End If
End Function
 
Private Sub cmdToggle_Click()
    Static bVisible As Boolean
    
    bVisible = Not IsVisibleInTheTaskbar(Me.hwnd)
    
    ShowInTheTaskbar Me.hwnd, bVisible
End Sub
 
Private Sub Form_Load()
    cmdToggle.Caption = "Toggle visibility"
    cmdCheck.Caption = "Check visibility"
End Sub