No you cannot change a property like that. You must use an API function to change it:

Code:
Private Declare Function SetWindowText Lib "user32" Alias "SetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String) As Long

Private Sub Command1_Click()

    SetWindowText Me.hwnd, "NewText"

End Sub
Also, the hDC property is a handle to the DC (Device Context) not the Window itself. The hWnd is the handle to the Window.