## Support for displaying markers

The org.eclipse.ui.ide.markerSupport extension point provides facilities for controlling how markers are displayed and organized in the UI. This extension point handles filters and grouping in views such as the Problems view.

Filters

The Problems view supports multiple filters at once. When multiple filters are enabled, any marker that matches one or more filters will be displayed. New filters can be added using the `problemFilter` element or manually by the user. Below is the filters section of the Problems view showing user filters and filters added via the extension point (system filters).

Groups

Markers can be grouped in two ways. The first way is to group marker types into groups using the `markerTypeCategory` element. This is shown when the user selects Group By > Type. Below is an example showing Java Problems and some using a test grouping.

When marker types are grouped together they will be shown in those groups in the filters dialog.

You can also create your own grouping using the `markerGrouping` element, which will show up as an extra entry in the Group By menu of the Problems view. The IDE provides a grouping based on severity (the default). The Java development tools provide a Java Type grouping.

`markerGroupings` are resolved by checking attributes on the IMarker. `markerAttributeMappings` are used to specify these mappings. Below is the Group By menu with the extra `markerGroupings` that have been added. The Problems view is currently grouped by severity.