Mdiform sobrepor a barra de tarefa, tem como?

Se vc marcar propriedade autoHide da barra naum funciona eu uso assim e trabalho com form em tela inteira, pra mim é o bastante

Veja esta dica do Ednei aqui no vbweb:

 

'Em General Declarations coloque isto,

Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpexecuta As String, ByVal lpWindowName As String) As Long

Private Declare Function ShowWindow Lib "user32" (ByVal hwnd As _
Long, ByVal nCmdShow As Long) As Long

Const SW_HIDE = 0: Const SW_SHOWNORMAL = 1

'*******************************************************






'AGORA  NO FORM COLOQUE ISTO,
'2 CommandButtons

Private Sub Command1_Click()
'Para Ocultar a barra de tarefas:

Dim aviso As Long
Dim janela As Long
Dim executa As String

executa = Space(256)
executa = "Shell_TrayWnd"

janela = FindWindow(executa, vbNullString)
aviso = ShowWindow(janela, SW_HIDE) 'Esconde a barra


End Sub

Private Sub Command2_Click()
'Para Mostrar a barra de tarefas:

Dim aviso As Long
Dim janela As Long
Dim executa As String

executa = Space(256)
executa = "Shell_TrayWnd"

janela = FindWindow(executa, vbNullString)
aviso = ShowWindow(janela, SW_SHOWNORMAL) 'Mostra a barra
End Sub

vlu//