119    QMenu *advancedMenu();
 
  148    void loadSymbol( 
QgsSymbol *symbol, SymbolLayerItem *parent = 
nullptr ) 
SIP_SKIP;
 
  155    void moveLayerDown();
 
  180    void duplicateLayer();
 
  191    void updateLayerPreview();
 
  196    void updatePreview();
 
  199    void symbolChanged();
 
  212    void symbolModified();
 
  220    void projectDataChanged();
 
  225    void layersAboutToBeRemoved( const QList<
QgsMapLayer *> &layers );
 
  242    void updateLockButton();
 
  244    void updateLockButtonIcon();
 
  246    SymbolLayerItem *currentLayerItem();
 
  258    void moveLayerByOffset( 
int offset );
 
  264    void setWidget( QWidget *widget );
 
  268    std::unique_ptr< 
QgsSymbol > mOwnedSymbol;
 
  269    QMenu *mAdvancedMenu = 
nullptr;
 
  270    QAction *mLockColorAction = 
nullptr;
 
  271    QAction *mLockSelectionColorAction = 
nullptr;
 
  274    QStandardItemModel *mSymbolLayersModel = 
nullptr;
 
  275    QWidget *mPresentWidget = 
nullptr;
 
  277    std::unique_ptr<DataDefinedRestorer> mDataDefineRestorer;
 
  281    bool mBlockModified = false;
 
 
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...