Bug 329930 Resetting a perspective while its active part is not defined in the perspective causes the perspective to not have an active part after the reset
1. Window > Show View > Console 2. Window > Reset Perspective... > OK 3. No parts are active.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartActivationHistory.java
return candidate;
				}
			}
		}
		return null;
	}
	MPart getNextActivationCandidate(Collection<MPart> validParts, MPart part) {
		MArea area = isInArea(part);
		if (area != null) {
			
			MPart candidate = getSiblingActivationCandidate(part);
			if (candidate != null) {
				return candidate;
			}
			
			candidate = findActivationCandidate(
					modelService.findElements(area, null, MPart.class, null), part);
			if (candidate != null) {
				return candidate;
			}
		}
		
		Collection<MPart> validCandidates = new ArrayList<MPart>();
		for (MPart validPart : generalActivationHistory) {
			if (validParts.contains(validPart)) {
				validCandidates.add(validPart);
			}
		}
		MPart candidate = findActivationCandidate(validCandidates, part);