void QTreeWidget::itemPressed(QTreeWidgetItem * item, int column)

This signal is emitted when the user presses a mouse button inside the widget.

The specified item is the item that was clicked, or 0 if no item was clicked. The column is the item's column that was clicked, or -1 if no item was clicked.

When I connect itemPressed to My slot void EditCurrentItem(QTreeWidgetItem* currentItem, int column):

connect(m_ui.m_TreeWidget,SIGNAL(itemPressed(QTreeWidgetItem*, int)),this,SLOT(EditCurrentItem(QTreeWidgetItem*, int)));

if the item that was clicked the sinal will be emitted. But when I cancel click item(click on the blank space Inside the TreeWidget), no itemPressed be emit? I don't knowWhy.

the SLOT void EditCurrentItem(QTreeWidgetItem* currentItem, int column) as below:

void QuesManager::EditCurrentItem(QTreeWidgetItem* currentItem, int column)
{
	if(currentItem != 0)
	{
		m_ui.m_Title->setText(currentItem->text(2));
		m_ui.m_Ans->setText(currentItem->text(3));
	}
	else
	{
		m_ui.m_Title->setText("");
		m_ui.m_Ans->setText("");
	}
}

The small project had been upload to the Attachment.(My Qt version is 5.5 and using VS2010)
Thanks help me!

See Attachment:
https://github.com/ljcduo/TempAns1