Bug 329930 Resetting a perspective while its active part is not defined in the perspective causes the perspective to not have an active part after the reset
1. Window > Show View > Console 2. Window > Reset Perspective... > OK 3. No parts are active.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/workbench/modeling/EPartService.java
* Creates a new placeholder for a part of the given id.
	 * 
	 * @param id
	 *            the identifier of the part, must not be <code>null</code>
	 * @return a new part of the given id, or <code>null</code> if no part descriptors can be found
	 *         that match the specified id
	 */
	public MPlaceholder createSharedPart(String id);
	/**
	 * Creates a new placeholder for a part of the given id.
	 * 
	 * @param id
	 *            the identifier of the part, must not be <code>null</code>
	 * @param force
	 *            <code>true</code> if a new part should be created, <code>false</code> if the
	 *            window should be queried for a shared part first
	 * @return a new part of the given id, or <code>null</code> if no part descriptors can be found
	 *         that match the specified id
	 */
	public MPlaceholder createSharedPart(String id, boolean force);
	/**
	 * Shows a part with the identified by the given id. In the event that there are multiple parts
	 * with the specified id, the client is recommended to use {@link #getParts()} and iterate over
	 * the collection to find the interested part and invoke {@link #showPart(MPart, PartState)} on
	 * it. The behavior of this method is dictated by the supplied state.
	 * <ul>
	 * <li>If <code>ACTIVATE</code> is supplied, then the part is made visible and granted focus.</li>
	 * <li>If <code>VISIBLE</code> is supplied, then the part will be made visible and possibly be
	 * granted focus depending on where it is relative to the active part. If it is in the same
	 * stack as the currently active part, then it will be granted focus.</li>