The Microsoft Windows operating environment identifies each form in an application by assigning it a handle, or hWnd. The hWnd property is used with Windows API calls. Many Windows operating environment functions require the hWnd of the active window as an argument. Because the value of this property can change while a program is running, you cannot rely on its value (e.g., when stored in a variable). Use the hWndPane property to retrieve the handle of the pane when control includes splitters.