C++ (Qt)
#include <QApplication>
#include <QComboBox>
#include <QStandardItemModel>
#include <QStylePainter>
 
class ComboBox : public QComboBox
{
public:
	ComboBox( QWidget* p = 0 ) : QComboBox( p ) {}
 
protected:
	void paintEvent( QPaintEvent* )
	{
		QModelIndex mi = model()->index( currentIndex(), 0 );
		QPalette pal = palette();
 
		QVariant v = mi.data( Qt::BackgroundRole );
		if( v.isValid() )
			pal.setColor( QPalette::Button, qvariant_cast< QColor >( v ) );
		v = mi.data( Qt::ForegroundRole );
		if( v.isValid() )
			pal.setColor( QPalette::ButtonText, qvariant_cast< QColor >( v ) );
 
		QStylePainter painter( this );
 
		QStyleOptionComboBox opt;
		initStyleOption( &opt );
		opt.palette = pal;
 
		painter.drawComplexControl( QStyle::CC_ComboBox, opt );
		painter.drawControl( QStyle::CE_ComboBoxLabel, opt );
	}
};
 
int main( int argc, char** argv )
{
	QApplication app( argc, argv );
 
	ComboBox cb;
	char *colors[] = { "brown", "orange", "yellow", "green", "lightblue", "blue", "purple" };
	QStandardItemModel* m = qobject_cast< QStandardItemModel* >( cb.model() );
 
	m->setRowCount( 7 );
	for( int i = 0; i < 7; i++ )
	{
		QModelIndex mi = m->index( i, 0 );
		m->setData( mi, colors[i], Qt::DisplayRole );
		QColor c = QColor( colors[i] );
		m->setData( mi, c, Qt::BackgroundRole );
		m->setData( mi, QColor( qGray( c.rgb() ) < 128 ? Qt::white : Qt::black ), Qt::ForegroundRole );
		m->setData( mi, c, Qt::DecorationRole );
	}
 
	cb.show();
	return app.exec();
}