WS_EX_TOOLWINDOW Creates a tool window, which is a window intended to be used as a floating toolbar. A tool window has a title bar that is shorter than a normal title bar, and the window title is drawn using a smaller font. A tool window does not appear in the task bar or in the window that appears when the user presses ALT+TAB.
PreTranslateMessage 这种方法不好吧..不是效率很低吗.