Bug 24212 [Tasks view] Support read-only tasks in Task list
JDT has now support for generating tasks from source, e.g. //TODO will add a task and show it in the task list. Such tasks can only be edited and changed in the source code. For this reason we would like to have support in the task list for such non-modifiable tasks. For example, we could add a marker attribute "read-only" and if this attribute is set then menu actions to delete or change the task will be disabled.
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/tasklist/MarkerUtil.java
case IMarker.SEVERITY_ERROR:
				return getImage("error");
			case IMarker.SEVERITY_WARNING:
				return getImage("warn");
			case IMarker.SEVERITY_INFO:
				return getImage("info");
		}
	}
	else if (isMarkerType(marker, IMarker.TASK)) {
		return getImage("task");
	}
	return null;
}
/**
 * Returns the image descriptor with the given key, or <code>null</code> if not found.
 */
static ImageDescriptor getImageDescriptor(String key) {
	ImageDescriptor desc = (ImageDescriptor) imageDescriptors.get(key);
	if (desc == null) {
		System.err.println("TaskList: No image descriptor for " + key); 
	}
	return desc;
}
/**
 * Returns the text for the line and location column given the marker.
 */
public static String getLineAndLocation(IMarker marker) {
	int lineNumber = getLineNumber(marker);
	String location = getLocation(marker);
	return getLineAndLocation(lineNumber, location);