diff --git a/python/gui/qgsfieldcombobox.sip b/python/gui/qgsfieldcombobox.sip
index ceef9363f73a..87173fb008b3 100644
--- a/python/gui/qgsfieldcombobox.sip
+++ b/python/gui/qgsfieldcombobox.sip
@@ -23,13 +23,13 @@ class QgsFieldComboBox : QComboBox
     void setFilters( QgsFieldProxyModel::Filters filters );
 
     //! currently used filter on list of fields
-    QgsFieldProxyModel::Filters filters();
+    QgsFieldProxyModel::Filters filters() const;
 
     //! return the currently selected field
-    QString currentField();
+    QString currentField() const;
 
     //! Returns the currently used layer
-    QgsVectorLayer* layer();
+    QgsVectorLayer* layer() const;
 
   signals:
     //! the signal is emitted when the currently selected field changes
diff --git a/python/gui/qgsfieldexpressionwidget.sip b/python/gui/qgsfieldexpressionwidget.sip
index b145ebdae36b..613b8127e45e 100644
--- a/python/gui/qgsfieldexpressionwidget.sip
+++ b/python/gui/qgsfieldexpressionwidget.sip
@@ -23,7 +23,7 @@ class QgsFieldExpressionWidget : QWidget
     void setLeftHandButtonStyle( bool isLeft );
 
     //! currently used filter on list of fields
-    QgsFieldProxyModel::Filters filters();
+    QgsFieldProxyModel::Filters filters() const;
 
     //! set the geometry calculator used in the expression dialog
     void setGeomCalculator( const QgsDistanceArea &da );
@@ -33,21 +33,21 @@ class QgsFieldExpressionWidget : QWidget
      * @param isExpression determines if the string returned is the name of a field or an expression
      * @param isValid determines if the expression (or field) returned is valid
      */
-    QString currentField( bool *isExpression = 0, bool *isValid = 0 );
+    QString currentField( bool *isExpression = 0, bool *isValid = 0 ) const;
 
     /**
       * Return true if the current expression is valid
       */
-    bool isValidExpression( QString *expressionError = 0 );
+    bool isValidExpression( QString *expressionError = 0 ) const;
 
-    bool isExpression();
+    bool isExpression() const;
     /**
       * Return the current text that is set in the expression area
       */
-    QString currentText();
+    QString currentText() const;
 
     //! Returns the currently used layer
-    QgsVectorLayer* layer();
+    QgsVectorLayer* layer() const;
 
   signals:
     //! the signal is emitted when the currently selected field changes
diff --git a/python/gui/qgsmaplayeractionregistry.sip b/python/gui/qgsmaplayeractionregistry.sip
index e7e537deacfc..09d1cf857091 100644
--- a/python/gui/qgsmaplayeractionregistry.sip
+++ b/python/gui/qgsmaplayeractionregistry.sip
@@ -34,7 +34,7 @@ class QgsMapLayerAction : QAction
 
     /** Define the targets of the action */
     void setTargets( Targets targets );
-    Targets targets() const;
+    const Targets& targets() const;
 
   signals:
     /** Triggered when action has been run for a specific feature */
diff --git a/python/gui/qgsmaplayercombobox.sip b/python/gui/qgsmaplayercombobox.sip
index cd0f7e4e66b9..475cee12c78c 100644
--- a/python/gui/qgsmaplayercombobox.sip
+++ b/python/gui/qgsmaplayercombobox.sip
@@ -20,7 +20,7 @@ class QgsMapLayerComboBox : QComboBox
     void setFilters( QgsMapLayerProxyModel::Filters filters );
 
     //! currently used filter on list layers
-    QgsMapLayerProxyModel::Filters filters();
+    QgsMapLayerProxyModel::Filters filters() const;
 
     //! currentLayer returns the current layer selected in the combo box
     QgsMapLayer* currentLayer();
diff --git a/src/gui/qgsfieldcombobox.cpp b/src/gui/qgsfieldcombobox.cpp
index 4617ff41b657..ae5c0d134e59 100644
--- a/src/gui/qgsfieldcombobox.cpp
+++ b/src/gui/qgsfieldcombobox.cpp
@@ -46,7 +46,7 @@ void QgsFieldComboBox::setLayer( QgsVectorLayer *layer )
   mFieldProxyModel->sourceFieldModel()->setLayer( layer );
 }
 
-QgsVectorLayer *QgsFieldComboBox::layer()
+QgsVectorLayer *QgsFieldComboBox::layer() const
 {
   return mFieldProxyModel->sourceFieldModel()->layer();
 }
@@ -67,7 +67,7 @@ void QgsFieldComboBox::setField( QString fieldName )
   setCurrentIndex( -1 );
 }
 
-QString QgsFieldComboBox::currentField()
+QString QgsFieldComboBox::currentField() const
 {
   int i = currentIndex();
 
diff --git a/src/gui/qgsfieldcombobox.h b/src/gui/qgsfieldcombobox.h
index 70fa1af7f2c9..2c5b5f14661f 100644
--- a/src/gui/qgsfieldcombobox.h
+++ b/src/gui/qgsfieldcombobox.h
@@ -47,13 +47,13 @@ class GUI_EXPORT QgsFieldComboBox : public QComboBox
     void setFilters( QgsFieldProxyModel::Filters filters );
 
     //! currently used filter on list of fields
-    QgsFieldProxyModel::Filters filters() { return mFieldProxyModel->filters(); }
+    QgsFieldProxyModel::Filters filters() const { return mFieldProxyModel->filters(); }
 
     //! return the currently selected field
-    QString currentField();
+    QString currentField() const;
 
     //! Returns the currently used layer
-    QgsVectorLayer* layer();
+    QgsVectorLayer* layer() const;
 
   signals:
     //! the signal is emitted when the currently selected field changes
diff --git a/src/gui/qgsfieldexpressionwidget.cpp b/src/gui/qgsfieldexpressionwidget.cpp
index 4c5f8ca5d95b..ee3d47c83275 100644
--- a/src/gui/qgsfieldexpressionwidget.cpp
+++ b/src/gui/qgsfieldexpressionwidget.cpp
@@ -83,24 +83,24 @@ void QgsFieldExpressionWidget::setGeomCalculator( const QgsDistanceArea &da )
   mDa = QSharedPointer<const QgsDistanceArea>( new QgsDistanceArea( da ) );
 }
 
-QString QgsFieldExpressionWidget::currentText()
+QString QgsFieldExpressionWidget::currentText() const
 {
   return mCombo->currentText();
 }
 
-bool QgsFieldExpressionWidget::isValidExpression( QString *expressionError )
+bool QgsFieldExpressionWidget::isValidExpression( QString *expressionError ) const
 {
   QString temp;
   QgsVectorLayer* vl = layer();
   return QgsExpression::isValid( currentText(), vl ? vl->pendingFields() : QgsFields(), expressionError ? *expressionError : temp );
 }
 
-bool QgsFieldExpressionWidget::isExpression()
+bool QgsFieldExpressionWidget::isExpression() const
 {
   return !mFieldProxyModel->sourceFieldModel()->isField( currentText() );
 }
 
-QString QgsFieldExpressionWidget::currentField( bool *isExpression , bool *isValid )
+QString QgsFieldExpressionWidget::currentField( bool *isExpression , bool *isValid ) const
 {
   QString text = currentText();
   if ( isValid )
@@ -114,7 +114,7 @@ QString QgsFieldExpressionWidget::currentField( bool *isExpression , bool *isVal
   return text;
 }
 
-QgsVectorLayer *QgsFieldExpressionWidget::layer()
+QgsVectorLayer *QgsFieldExpressionWidget::layer() const
 {
   return mFieldProxyModel->sourceFieldModel()->layer();
 }
diff --git a/src/gui/qgsfieldexpressionwidget.h b/src/gui/qgsfieldexpressionwidget.h
index 395d7767e72c..ce96ffa07688 100644
--- a/src/gui/qgsfieldexpressionwidget.h
+++ b/src/gui/qgsfieldexpressionwidget.h
@@ -62,7 +62,7 @@ class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
     void setLeftHandButtonStyle( bool isLeft );
 
     //! currently used filter on list of fields
-    QgsFieldProxyModel::Filters filters() { return mFieldProxyModel->filters(); }
+    QgsFieldProxyModel::Filters filters() const { return mFieldProxyModel->filters(); }
 
     //! set the geometry calculator used in the expression dialog
     void setGeomCalculator( const QgsDistanceArea &da );
@@ -72,21 +72,21 @@ class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
      * @param isExpression determines if the string returned is the name of a field or an expression
      * @param isValid determines if the expression (or field) returned is valid
      */
-    QString currentField( bool *isExpression = 0, bool *isValid = 0 );
+    QString currentField( bool *isExpression = 0, bool *isValid = 0 ) const;
 
     /**
       * Return true if the current expression is valid
       */
-    bool isValidExpression( QString *expressionError = 0 );
+    bool isValidExpression( QString *expressionError = 0 ) const;
 
-    bool isExpression();
+    bool isExpression() const;
     /**
       * Return the current text that is set in the expression area
       */
-    QString currentText();
+    QString currentText() const;
 
     //! Returns the currently used layer
-    QgsVectorLayer* layer();
+    QgsVectorLayer* layer() const;
 
   signals:
     //! the signal is emitted when the currently selected field changes
diff --git a/src/gui/qgsmaplayeractionregistry.h b/src/gui/qgsmaplayeractionregistry.h
index 905314f78f63..ad760bf635a4 100644
--- a/src/gui/qgsmaplayeractionregistry.h
+++ b/src/gui/qgsmaplayeractionregistry.h
@@ -70,7 +70,7 @@ class GUI_EXPORT QgsMapLayerAction : public QAction
     /** Define the targets of the action */
     void setTargets( Targets targets ) {mTargets = targets;}
     /** Return availibity of action */
-    Targets targets() const {return mTargets;}
+    const Targets& targets() const {return mTargets;}
 
   signals:
     /** Triggered when action has been run for a specific list of features */
diff --git a/src/gui/qgsmaplayercombobox.h b/src/gui/qgsmaplayercombobox.h
index b2b160b718fe..8d5648af6cbf 100644
--- a/src/gui/qgsmaplayercombobox.h
+++ b/src/gui/qgsmaplayercombobox.h
@@ -44,7 +44,7 @@ class GUI_EXPORT QgsMapLayerComboBox : public QComboBox
     void setFilters( QgsMapLayerProxyModel::Filters filters );
 
     //! currently used filter on list layers
-    QgsMapLayerProxyModel::Filters filters() { return mProxyModel->filters(); }
+    QgsMapLayerProxyModel::Filters filters() const { return mProxyModel->filters(); }
 
     //! currentLayer returns the current layer selected in the combo box
     QgsMapLayer* currentLayer();