EnableExplicit Define a Global ListIconCB Procedure ListIconCB(hWnd, uMsg, wParam, lParam) Select uMsg Case #WM_VSCROLL Debug "Vertikal" Case #WM_HSCROLL Debug "Horizontal" EndSelect ProcedureReturn CallWindowProc_(ListIconCB, hWnd, uMsg, wParam, lParam) EndProcedure If OpenWindow(0, 0, 0, 500, 400, "Window", #PB_Window_SystemMenu | #PB_Window_ScreenCentered) ListIconGadget(1, 0, 0, 500, 400, "Column", 1000, 0) For a=1 To 250 AddGadgetItem(1, -1, "Item " + Str(a), 0, 0) Next ListIconCB = SetWindowLongPtr_(GadgetID(1), #GWL_WNDPROC, @ListIconCB()) Repeat Select WaitWindowEvent() Case #PB_Event_CloseWindow End EndSelect ForEver EndIf