Bug 322356 EPS's isPartVisible(MPart) method does not consider placeholders
SSIA
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
* 
	 * @see org.eclipse.e4.ui.workbench.modeling.EPartService#getDirtyParts()
	 */
	public Collection<MPart> getDirtyParts() {
		List<MPart> dirtyParts = new ArrayList<MPart>();
		for (MPart part : getParts()) {
			if (part.isDirty()) {
				dirtyParts.add(part);
			}
		}
		return dirtyParts;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.ui.workbench.modeling.EPartService#save(org.eclipse.e4.ui.model.application.
	 * MSaveablePart, boolean)
	 */
	public boolean savePart(MPart part, boolean confirm) {
		if (!part.isDirty()) {
			return true;
		}
		if (confirm && saveHandler != null) {
			switch (saveHandler.promptToSave(part)) {
			case NO:
				return true;
			case CANCEL:
				return false;
			}