The drag and moving problem??

[Ray]

I am planning to build a tool bar like Dr.eye,when using the Qt's example D&D ,I set set the program like this:

MainWidget::MainWidget(QWidget *parent) : QLabel(parent)
{
    setWindowState(this->windowState() ^ Qt::WindowFullScreen);
    setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
    setAcceptDrops(true);
 
    toolbar = new ToolWidget(this);
    toolbar->move(50, 50);
    toolbar->show();
    toolbar->setAttribute(Qt::WA_DeleteOnClose); 
}
 
void MainWidget::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {       	
        if (event->source() == this) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } else 
        {
            event->acceptProposedAction();
        }
    } 
    else 
    {
        event->ignore();
    }
}
 
void MainWidget::dragMoveEvent(QDragMoveEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {
        if (children().contains(event->source())) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } 
        else 
        {
            event->acceptProposedAction();
        }
        printf("this is the test\n");
    } 
    else 
    {
        event->ignore();
    }
}
 
void MainWidget::dropEvent(QDropEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {
        QByteArray itemData = event->mimeData()->data("MyToolBar");
        QDataStream dataStream(&itemData, QIODevice::ReadOnly);
 
        QPixmap pixmap;
        QPoint offset;
        dataStream >> pixmap >> offset;
 
        ToolWidget *Transfer = new ToolWidget(this);
        Transfer->setPixmap(pixmap);
        Transfer->move(event->pos() - offset);
        Transfer->show();
        Transfer->setAttribute(Qt::WA_DeleteOnClose);
 
        if (event->source() == this) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } else {
            event->acceptProposedAction();
        }
    } 
    else 
    {
        event->ignore();
    }
}
 
void MainWidget::mousePressEvent(QMouseEvent *event)
{
	if(Qt::LeftButton == event->button ())
	{
	    ToolWidget *child = static_cast<ToolWidget*>(childAt(event->pos()));
	    if (!child)
	        return;
 
	    QPixmap pixmap = *child->pixmap();  //get the pixmap on the label
 
 
	    QByteArray itemData;
	    QDataStream dataStream(&itemData, QIODevice::WriteOnly);
	    dataStream << pixmap << QPoint(event->pos() - child->pos());
 
	    QMimeData *mimeData = new QMimeData;
	    mimeData->setData("MyToolBar", itemData);
	    child->hide();
 
	    QDrag *drag = new QDrag(this);
	    drag->setMimeData(mimeData);
	    drag->setPixmap(pixmap);
	    drag->setHotSpot(event->pos() - child->pos());
 
	    if (drag->start(Qt::MoveAction) == Qt::MoveAction)
	        child->close();
	    else 
	        child->show();
    }
}

MainWidget::MainWidget(QWidget *parent) : QLabel(parent)
{
    setWindowState(this->windowState() ^ Qt::WindowFullScreen);
    setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
    setAcceptDrops(true);
    
    toolbar = new ToolWidget(this);
    toolbar->move(50, 50);
    toolbar->show();
    toolbar->setAttribute(Qt::WA_DeleteOnClose); 
}

void MainWidget::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {       	
        if (event->source() == this) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } else 
        {
            event->acceptProposedAction();
        }
    } 
    else 
    {
        event->ignore();
    }
}

void MainWidget::dragMoveEvent(QDragMoveEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {
        if (children().contains(event->source())) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } 
        else 
        {
            event->acceptProposedAction();
        }
        printf("this is the test\n");
    } 
    else 
    {
        event->ignore();
    }
}

void MainWidget::dropEvent(QDropEvent *event)
{
    if (event->mimeData()->hasFormat("MyToolBar")) 
    {
        QByteArray itemData = event->mimeData()->data("MyToolBar");
        QDataStream dataStream(&itemData, QIODevice::ReadOnly);
        
        QPixmap pixmap;
        QPoint offset;
        dataStream >> pixmap >> offset;

        ToolWidget *Transfer = new ToolWidget(this);
        Transfer->setPixmap(pixmap);
        Transfer->move(event->pos() - offset);
        Transfer->show();
        Transfer->setAttribute(Qt::WA_DeleteOnClose);

        if (event->source() == this) 
        {
            event->setDropAction(Qt::MoveAction);
            event->accept();
        } else {
            event->acceptProposedAction();
        }
    } 
    else 
    {
        event->ignore();
    }
}

void MainWidget::mousePressEvent(QMouseEvent *event)
{
	if(Qt::LeftButton == event->button ())
	{
	    ToolWidget *child = static_cast<ToolWidget*>(childAt(event->pos()));
	    if (!child)
	        return;
	
	    QPixmap pixmap = *child->pixmap();  //get the pixmap on the label
	    	    
	
	    QByteArray itemData;
	    QDataStream dataStream(&itemData, QIODevice::WriteOnly);
	    dataStream << pixmap << QPoint(event->pos() - child->pos());
	
	    QMimeData *mimeData = new QMimeData;
	    mimeData->setData("MyToolBar", itemData);
	    child->hide();
	        
	    QDrag *drag = new QDrag(this);
	    drag->setMimeData(mimeData);
	    drag->setPixmap(pixmap);
	    drag->setHotSpot(event->pos() - child->pos());
	    
	    if (drag->start(Qt::MoveAction) == Qt::MoveAction)
	        child->close();
	    else 
	        child->show();
    }
}

To copy to clipboard, switch view to plain text mode 

this is following the example,but I create a class ToolWidget,
it contains several button's。
the question is,when i drag and move the toolbar, all of the object except toolbar'r 's icon
are invisiable
is it possible make the label visible,and how to do it??