Bug 320285 Messages inteneded for developers in the error log
The message "unsupported: isEditorAreaVisible" appears in the error log during the normal run of e4 SDK. (For instance, starting the e4 SDK on an clean workspace produces two of those messages.)
bundles/org.eclipse.e4.ui.workbench.addons.swt/src/org/eclipse/e4/ui/workbench/addons/perspectiveswitcher/PerspectiveSwitcher.java
public void widgetSelected(SelectionEvent e) {
				MPerspective persp = (MPerspective) e.widget.getData();
				persp.getParent().setSelectedElement(persp);
			}
			public void widgetDefaultSelected(SelectionEvent e) {
				MPerspective persp = (MPerspective) e.widget.getData();
				persp.getParent().setSelectedElement(persp);
			}
		});
		psItem.addListener(SWT.MenuDetect, new Listener() {
			public void handleEvent(org.eclipse.swt.widgets.Event event) {
				MPerspective persp = (MPerspective) event.widget.getData();
				openMenuFor(psItem, persp);
			}
		});
		
		psTB.pack();
		psTB.getShell().layout(new Control[] { psTB }, SWT.DEFER);
		return psItem;
	}
	
	private IPerspectiveDescriptor getDescriptorFor(String id) {
		return PlatformUI.getWorkbench().getPerspectiveRegistry().findPerspectiveWithId(id);
	}
	private MPerspective getPerspectiveFor(IPerspectiveDescriptor desc) {
		MPerspectiveStack stack = getPerspectiveStack();
		if (stack != null) {
			
			for (MPerspective persp : stack.getChildren()) {
				if (persp.getElementId().equals(desc.getId())) {