QComboBox{ background-color: red}QComboBox:on{ background-color: green}
QSize CComboBoxPopupItemDelegate::sizeHint(const QStyleOptionViewItem&, const QModelIndex &) const { return QSize(200, 60);}
combo_box_->view()->setItemDelegate(new CComboBoxPopupItemDelegate(this));
CSSQComboBox QListView::item { margin: 20px }
QComboBox QAbstractItemView::item { margin-top: 25px; }
combobox->setItemDelegate(new QStyledItemDelegate);