Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Const BM_SETSTATE = &HF3
Dim flag As Boolean
Private Sub Command1_Click()
flag = Not flag
SendMessage Command1.hwnd, BM_SETSTATE, flag, ByVal 0&
End Sub