PowerBuilder, disable system menu`s close button

ulong ll_parent_hwnd
ulong ll_sys_menu_hwnd
ulong ll_sys_menu_close_flags
ulong ll_ret

n_cst_numerical u_num

ll_parent_hwnd = Handle(this.parentwindow())

ll_sys_menu_hwnd = GetSystemMenu(ll_parent_hwnd, FALSE)

ll_sys_menu_close_flags = GetMenuState(ll_sys_menu_hwnd, SC_CLOSE, MF_BYCOMMAND )

ll_ret = u_num.of_bitwiseand(ll_sys_menu_close_flags , MF_DISABLED)

ib_close_prev_enabled = (ll_ret = 0)

If ib_close_prev_enabled Then
EnableMenuItem (ll_sys_menu_hwnd, SC_CLOSE, MF_BYCOMMAND + MF_DISABLED + MF_GRAYED)
End If

 

And to enable it later:

If ib_close_prev_enabled Then
EnableMenuItem (GetSystemMenu(handle(parentwindow()), FALSE), SC_CLOSE, MF_BYCOMMAND + MF_ENABLED)
End If