Bug 328946 Part activation history may return incorrect candidate if no placeholders could be found in a perspective
1. Window > Open Perspective > Other... > CVS Repository Exploring 2. Hide the 'CVS Repositories' view. 3. The 'History' view should become active, it is not.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartActivationHistory.java
}
	private MPart getSiblingActivationCandidate(MPart part) {
		MPlaceholder placeholder = part.getCurSharedRef();
		MUIElement candidate = getSiblingSelectionCandidate(part, placeholder == null ? part
				: placeholder);
		return (MPart) (candidate instanceof MPlaceholder ? ((MPlaceholder) candidate).getRef()
				: candidate);
	}
	private MUIElement getSiblingSelectionCandidate(MPart part, MUIElement element) {
		List<MUIElement> siblings = element.getParent().getChildren();
		for (MPart previouslyActivatedPart : generalActivationHistory) {
			if (previouslyActivatedPart != part && previouslyActivatedPart.isToBeRendered()) {
				if (siblings.contains(previouslyActivatedPart)) {
					return previouslyActivatedPart;
				}
				MPlaceholder placeholder = partService.getLocalPlaceholder(previouslyActivatedPart);
				if (placeholder != null && placeholder.isToBeRendered()
						&& siblings.contains(placeholder)) {
					return placeholder;
				}
			}
		}
		return null;
	}
	MUIElement getSiblingSelectionCandidate(MPart part) {
		MPlaceholder placeholder = part.getCurSharedRef();
		return getSiblingSelectionCandidate(part, placeholder == null ? part : placeholder);
	}
}