ode
QList<QtilitiesCategory> displayed_categories;
displayed_categories << QtilitiesCategory("Category 1");
observer_widget->activeHints()->setDisplayedCategories(displayed_categories);
observer_widget->activeHints()->setCategoryFilterEnabled(true);
\endcode

After adding the category filter, the observer widget looks this:

\image html observer_widget_doc_tree_view_category_filter.jpg "Observer Widget With Filtered Categories (Tree View Mode)"

\subsection controlling_activity Controlling activity

In the 