Qt 窗口指針調用close()方法之後，還能使用指針嗎？？
QWidget *w = new QWidget(this);
w->close();
那麼：w->isVisible()？？？是什麼結果呢？true or false??? 還是crash??
先貼一段英語壯壯B格~~ 哈哈
Closes this widget. Returns true if the widget was closed; otherwise returns false.
First it sends the widget a QCloseEvent. The widget is hidden if it accepts the close event. If it ignores the event, nothing happens. The default implementation of QWidget::closeEvent() accepts the close event.
If the widget has the Qt::WA_DeleteOnClose flag, the widget is also deleted. A close events is delivered to the widget no matter if the widget is visible or not.
The QApplication::lastWindowClosed() signal is emitted when the last visible primary window (i.e. window with no parent) with the Qt::WA_QuitOnClose attribute set is closed. By default this attribute is set for all widgets except transient windows such as splash screens, tool windows, and popup menus.
答案是：false，close()可以理解爲hide()