+ bool isActive();
+
+ /// Initializes the operation presentation by the parameter object and display the presentation
+ /// \param theObject an operation feature source to fill the presentation
+ /// \param theUpdateViewer the parameter whether the viewer should be update immediatelly
+ /// \returns true if the presentation is displayed
+ bool activate(const FeaturePtr& theObject, const bool theUpdateViewer);
+
+ /// Initializes the operation presentation by empty object and erase the presentation
+ /// \param theUpdateViewer the parameter whether the viewer should be update immediatelly
+ /// \returns true if the presentation has been displayed and now it is erased
+ bool deactivate(const bool theUpdateViewer);
+
+ /// If the presentation is active[displayed], the shapes of the presentation is recomputed
+ /// and the presentation is redisplayed.
+ /// \param theUpdateViewer the parameter whether the viewer should be update immediatelly
+ /// \returns true if the presentation is redisplayed
+ bool redisplay(const ObjectPtr& theObject, const bool theUpdateViewer);
+
+ /// Nullify the operation presentation. For example, it can be useful when the viewer/context
+ /// is closed. If this is not performed and the presentation is assigned in another context,
+ /// it caused erroneus case because the presentation has linkage to the previous context.
+ void clearPrs();