转自：http://www.2cto/kf/201302/191602.html

this->setWindowFlags(Qt::FramelessWindowHint);

#include <QMouseEvent>
protected:
    void mousePressEvent(QMouseEvent *e);
    void mouseMoveEvent(QMouseEvent *e);
    void mouseReleaseEvent(QMouseEvent *e);
private:
    QPoint last;

//可以在构造函数中初始一下last变量用其成员函数setX,setY就是了
//接下来就是对三个鼠标事件的重写
void MainWindow::mousePressEvent(QMouseEvent *e)
{
    last = e->globalPos();
}
void MainWindow::mouseMoveEvent(QMouseEvent *e)
{
    int dx = e->globalX() - last.x();
    int dy = e->globalY() - last.y();
    last = e->globalPos();
    move(x()+dx, y()+dy);
}
void MainWindow::mouseReleaseEvent(QMouseEvent *e)
{
    int dx = e->globalX() - last.x();
    int dy = e->globalY() - last.y();
    move(x()+dx, y()+dy);
}