#include <QtWidgets/QApplication>
#include <QtWidgets/QDialog>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QTableView>
#include <QtWidgets/QDirModel>

class MyDialog : public QDialog
{
public:

	MyDialog()
	{
		QVBoxLayout * layout = new QVBoxLayout;

		QPushButton * btnChangeBackground = new QPushButton( "change background" );
		layout->addWidget( btnChangeBackground );
		connect( btnChangeBackground, &QPushButton::clicked, this, &MyDialog::changeBackgroundSlot );

		layout->addWidget( &m_tableView );

		m_tableView.setModel( new QDirModel() );

		setLayout( layout );

		// comment this to make changeBackgroundSlot working correctly
		m_tableView.setStyleSheet( "QTableView { gridline-color: red }" );
		//
	}

	void changeBackgroundSlot()
	{
		QPalette currentPalette;

		currentPalette = m_tableView.palette();

		// trying to invert all ColorRoles, but without expected effect
		for ( int i = 0; i < QPalette::NColorRoles; ++i )
		{
			currentPalette.setColor( ( QPalette::ColorRole )i
				, invertColor( currentPalette.color( ( QPalette::ColorRole )i ) ) );
		}
		//

		m_tableView.setPalette( currentPalette );
	}

	QColor invertColor( QColor const & _color ) const
	{
		return QColor( 255 - _color.red(), 255 - _color.green(), 255 - _color.blue() );
	}

private:
	QTableView m_tableView;
};

int main( int _argc, char ** _argv )
{
	QApplication app( _argc, _argv );

	MyDialog dlg;
	dlg.show();

	return app.exec();	
}