Now I am using Qt5 to draw Kline of stocks. Two classes are defined for price bar and volume bar, then I add them to a widget by a QSplitter. However, When I move mouse forward or backward and the price-bar chart updates, the volume-bar section will not repaint simultaneously until I put mouse under volume widget. I tried some ideas, but it didn't work. Many thanks.

A part of codes like this:

    pvolume = new VolumeBar(this);
    pvolume->setObjectName(tr("volume_bar"));
    pvolume->setFocusPolicy(Qt::StrongFocus);

    pkline = new PriceBar(this);
    pkline->setObjectName("price_bar");
    pkline->setFocusPolicy(Qt::StrongFocus);


    QSplitter *splitterMain = new QSplitter(Qt::Vertical, 0); 

    splitterMain->insertWidget(0, pkline);
    splitterMain->insertWidget(1, pvolume);
    splitterMain->setStretchFactor(0, 4);
    splitterMain->setStretchFactor(1, 1);

For pricebar, the paintEvent function is overrided as follows,

void PriceBar::paintEvent(QPaintEvent *event)
{
    KLineGrid::paintEvent(event);  // parent of VolumeBar and PriceBar
    drawLine();  // draw price bar
}

For VolumeBar, it is overrided like this,

void VolumeBar::paintEvent(QPaintEvent *event)
{

    KLineGrid::paintEvent(event);
    
    drawYtick();  // y axis
    drawVolume();
}