Three tiny horizontal line top left corner always appearing (solved)

[houmingc]

I am sure other Qt developer must have notice the 3 tiny white horizontal line in one column top left corner.
I like to ask how to remove this three tiny white line.

Below is my code.
{
QPalette pal=palette();
pal.setColor(QPalette::Background, Qt::white);
setPalette(pal);
setAutoFillBackground(false);
m_pPalette= new QPalette();
m_pPixmap= new QPixmap(":/file/leftp.png");
m_pPalette->setBrush(QPalette:Background,QBrush(*m_pPixmap);
setPalette(*m_pPalette);
QWidget *centralWidget = new QWidget(this);
QGridLayout *layout = QGridLayout();
centralWidget->setLayout(layout);
}

[IamSumit]

Can you show an image?

[houmingc]

i am not sure how it was form, i managed to remove it in the Forms. Grateful this forum existed.
Thanks