Bug 327765 EPartService will hide a part of another perspective
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartActivationHistory.java
}
				}
				MElementContainer<MUIElement> parent = placeholder == null ? candidate.getParent()
						: placeholder.getParent();
				
				if (isValid(parent)) {
					
					
					if (parent instanceof MGenericStack<?>) {
						
						MUIElement element = parent.getSelectedElement();
						
						if (element instanceof MPlaceholder) {
							element = ((MPlaceholder) element).getRef();
						}
						
						if (element == part) {
							return candidate;
						}
						
						
						
						
						
						return element instanceof MPart ? (MPart) element : candidate;
					}
					return candidate;
				}
			}
		}