command.markSimilarTasksRead.name = Mark all Similar Tasks as Read 

command.markAllSimilarTasksRead.label = Read (all Similar Incomings)

            defaultHandler="org.eclipse.mylyn.internal.tasks.ui.commands.MarkTaskHandler$MarkSimilarTasksReadHandler"

            id="org.eclipse.mylyn.tasks.ui.command.markAllSimilarTasksRead"

            name="%command.markSimilarTasksRead.name">

      </command>

      <command

            categoryId="org.eclipse.mylyn.tasks.ui.commands"

                  commandId="org.eclipse.mylyn.tasks.ui.command.markAllSimilarTasksRead"

                  label="%command.markAllSimilarTasksRead.label"

                  style="push">

               <visibleWhen

                     checkEnabled="false">

                  <reference

                        definitionId="org.eclipse.mylyn.tasks.ui.expressions.repositoryElements">

                  </reference>

               </visibleWhen>

            </command>

            <command

import java.util.Collection;

import java.util.Iterator;

import org.eclipse.mylyn.internal.tasks.ui.notifications.TaskAttributeDiff;

import org.eclipse.mylyn.internal.tasks.ui.notifications.TaskDataDiff;

import org.eclipse.mylyn.internal.tasks.ui.notifications.TaskListNotifier;

import org.eclipse.mylyn.tasks.core.ITask.SynchronizationState;

	public static class MarkSimilarTasksReadHandler extends AbstractTaskHandler {

		@Override

		protected void execute(ExecutionEvent event, ITask currentTask) throws ExecutionException {

			//get incomings of the current task (only first level attributes)

			TaskListNotifier currentNotifier = new TaskListNotifier(TasksUiPlugin.getRepositoryModel(),

					TasksUiPlugin.getTaskDataManager());

			TaskDataDiff currentDiff = currentNotifier.getDiff(currentTask);

			if (currentDiff != null && TasksUiPlugin.getTaskList() != null) {

				//go through all tasks in tasklist of the given repository

				for (ITask otherTask : TasksUiPlugin.getTaskList().getTasks(currentTask.getRepositoryUrl())) {

					if (otherTask != currentTask

							&& otherTask.getSynchronizationState() == SynchronizationState.INCOMING) {

						boolean isSameChange = false;

						isSameChange = isEqualChangedAttributesSet(currentDiff, otherTask, isSameChange);

						if (isSameChange) {

							TasksUiPlugin.getTaskDataManager().setTaskRead(otherTask, true);

						}

					}

				}

			}

			TasksUiPlugin.getTaskDataManager().setTaskRead(currentTask, true);

		}

		private boolean isEqualChangedAttributesSet(TaskDataDiff currentDiff, ITask otherTask, boolean isSameChange) {

			//only check other tasks which have incomings for exactly the same set of changed attributes

			TaskListNotifier otherNotifier = new TaskListNotifier(TasksUiPlugin.getRepositoryModel(),

					TasksUiPlugin.getTaskDataManager());

			TaskDataDiff otherDiff = otherNotifier.getDiff(otherTask);

			Collection<TaskAttributeDiff> otherChangedAttributes = otherDiff.getChangedAttributes();

			if (otherDiff != null

					&& currentDiff.getChangedAttributes().size() == otherChangedAttributes.size()) {

				//same diff size, compare individual changed attributes

				Iterator<TaskAttributeDiff> currentIterator = currentDiff.getChangedAttributes().iterator();

				while (currentIterator.hasNext()) {

					TaskAttributeDiff currentAttributeDiff = currentIterator.next();

					Iterator<TaskAttributeDiff> otherIterator = otherChangedAttributes.iterator();

					while (otherIterator.hasNext()) {

						TaskAttributeDiff otherAttributeDiff = otherIterator.next();

						if (currentAttributeDiff.getNewAttribute()

								.getId()

								.equals(otherAttributeDiff.getNewAttribute().getId())) {

							//found a match, remove from other diff

							otherChangedAttributes.remove(otherAttributeDiff);

							break;

						}

					}

				}

				//if sets are equal, otherChangedAttributes should be empty now

				isSameChange = otherChangedAttributes.isEmpty();

			}

			return isSameChange;

		}

	}