Qt做一个简单的多文档编辑器，该实验的过程中主要涉及到Qt窗口的设计，菜单栏(包括右击菜单)，工具栏，状态栏，常见的文本文件等操作-Qt do a simple multi-document editor the Qt window design, the menu bar (including the right-click menu), mainly related to the process of the experiment, toolbar, status bar, common t