Qt将鼠标移动范围限定在某个区域内QCursor跨平台代码

不用ClipCursor()，直接上跨平台代码：

void MyMainWindow::leaveEvent(QEvent * event)
{
	// Get the window geometry & cursor position
	const QRect & rect = geometry();
	QPoint position = QCursor::pos();

	// Check the bounds
	qint32 x = qBound(rect.left(), position.x(), rect.right());
	qint32 y = qBound(rect.top(), position.y(), rect.bottom());

	// Adjust the cursor
	if (x != position.x() || y != position.y())
		QCursor::setPos(x, y);

	event->accept();
	QMainWindow::leaveEvent(event);
}