Bug 343003 Selection changes for shared parts may not be propagated if they were not originally rendered in the model
The search algorithm currently only iterates through containers for parts. This will not work for parts that are represented by placeholders.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/SelectionServiceImpl.java
private void track(final MPart part) {
		IEclipseContext context = part.getContext();
		if (context != null && tracked.add(context)) {
			context.runAndTrack(new RunAndTrack() {
				private boolean initial = true;
				public boolean changed(IEclipseContext context) {
					Object selection = context.get(OUT_SELECTION);
					if (initial) {
						initial = false;
						if (selection == null) {
							return true;
						}
					}
					if (activePart == part) {
						notifyListeners(part, selection);
					} else {
						notifyTargetedListeners(part, selection);
					}
					return true;
				}
			});
		}
	}
	void internalSetSelection(Object selection) {
		if (selection != null) {
			context.set(IServiceConstants.ACTIVE_SELECTION, selection);
		} else {
			context.remove(IServiceConstants.ACTIVE_SELECTION);
		}
	}