why do I need to claim this class in h file?

[sheeps]

My h file is like this:

• #ifndef WINDOW_H
  #define WINDOW_H
  #include <QMainWindow>
  #include <QUrl>
  #include <QWebElement>
  class QTreeWidgetItem; //====================================> why do I need this line?
  #include "ui_window.h"
  class Window : public QMainWindow, private Ui::Window
  {
  Q_OBJECT
  public:
  Window(QWidget *parent = 0);
  void setUrl(const QUrl &url);
  public slots:
  void on_webView_loadFinished();
  private:
  void examineChildElements(const QWebElement &parentElement,
  QTreeWidgetItem *parentItem);
  };
  #endif

[David.G]

It's a forward declaration. (a bit more about it here and here

[sheeps]

@David.G Thank you!