///
/// \brief 绘制左上角按钮
/// \param painter 设置好绘制设备的painter
/// \param btn 左上角按钮,左上角按钮指针，Painter已经把此按钮设置为此绘制设备
///
void DTableWidgetEx::paintConnerButton(QStylePainter &painter,QAbstractButton* btn)
{
QStyleOptionHeader opt;
opt.init(btn);
QStyle::State state = QStyle::State_None;
if (btn->isEnabled())
state |= QStyle::State_Enabled;
if (btn->isActiveWindow())
state |= QStyle::State_Active;
if (btn->isDown())
state |= QStyle::State_Sunken;
opt.state = state;
opt.rect = btn->rect();
opt.text = btn->text(); // this line is the only difference to QTableCornerButton
opt.position = QStyleOptionHeader::OnlyOneSection;
painter.drawControl(QStyle::CE_Header, opt);
}
