Opens the list of the control field currently selected in a dialogue box. These shortcut keys apply not only to combo boxes but also to icon buttons with pop-up menus. Close an opened list by pressing the Escape key.
在一个对话框内打开当前所选控制字段的列表。这个组合键既适用于组合框、也适用于带弹出式菜单的图标按钮。用 Esc 键可重新关闭已打开的列表。