Bug 320100 Package Explorer unexpectedly added to Debug perspective
1. Open a fresh e4 workbench 2. Leave the Package Explorer activated 3. Open the Debug perspective Result: The Debug perspective contains the Package Explorer, although this should not be the case. This does not happen when another view is activated before opening the Debug perspective.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java
Control ctrl = (Control) element.getWidget();
		if (ctrl != null && ctrl.getParent() != ctf) {
			ctrl.setParent(ctf);
			cti.setControl(ctrl);
		} else if (element.getWidget() == null) {
			Control tabCtrl = (Control) renderer.createGui(element);
			cti.setControl(tabCtrl);
		}
		ignoreTabSelChanges = true;
		ctf.setSelection(cti);
		ignoreTabSelChanges = false;
		
		if (ctf.getTopRight() != null) {
			Control curTB = ctf.getTopRight();
			ctf.setTopRight(null);
			MUIElement tbME = (MUIElement) curTB
					.getData(AbstractPartRenderer.OWNING_ME);
			if (tbME instanceof MRenderedToolBar)
				renderer.removeGui(tbME);
			else
				curTB.dispose();
		}
		
		MPart part = (MPart) ((element instanceof MPart) ? element
				: ((MPlaceholder) element).getRef());
		MMenu viewMenu = getViewMenu(part);
		MToolBar toolbar = part.getToolbar();
		if (toolbar == null) {
			if (viewMenu != null) {
				MRenderedToolBar rtb = MenuFactoryImpl.eINSTANCE