Bug 326177 EPartService's getActivePart() does not appear to work properly for an application with multiple windows
Based on the code in PartServiceCreationFunction, the EPartService implementation being returned when an application's context is queried seems to be a window-level EPartService implementation.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
private List<MPart> activatedParts = new ArrayList<MPart>();
		private List<MPart> deactivatedParts = new ArrayList<MPart>();
		private List<MPart> hiddenParts = new ArrayList<MPart>();
		private List<MPart> visibleParts = new ArrayList<MPart>();
		private int activated = 0;
		private int deactivated = 0;
		private int hidden = 0;
		private int visible = 0;
		private boolean valid = true;
		public void clear() {
			activated = 0;
			deactivated = 0;
			hidden = 0;
			visible = 0;
			activatedParts.clear();
			deactivatedParts.clear();
			hiddenParts.clear();
			visibleParts.clear();
			valid = true;
		}