'coloca esto en un módulo:
Public Const HWND_TOPMOST = -1
Public Const HWND_NOTOPMOST = -2
Public Const SWP_NOSIZE = &H1
Public Const SWP_NOMOVE = &H2
Public Const SWP_NOACTIVATE = &H10
Public Const SWP_SHOWWINDOW = &H40
Public Const SWP_HIDEWINDOW = &H80
Public 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
Coloca esto cuando quieras el Stay on top:
SetWindowPos forma.hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_SHOWWINDOW Or SWP_NOSIZE Or SWP_NOMOVE Or SWP_NOACTIVATE
Coloca esto cuando ya no quieras el Stay on top:
SetWindowPos forma.hwnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_SHOWWINDOW Or SWP_NOSIZE Or SWP_NOMOVE Or SWP_NOACTIVATE