Bug 299272 Renderer cannot handle an MPart with a null label
java.lang.IllegalArgumentException: Argument cannot be null at org.eclipse.swt.SWT.error(SWT.java:4049) at org.eclipse.swt.SWT.error(SWT.java:3983) at org.eclipse.swt.SWT.error(SWT.java:3954) at org.eclipse.e4.ui.widgets.CTabItem.setText(CTabItem.java:1013) at org.eclipse.e4.workbench.ui.renderers.swt.StackRenderer.showChild(StackRenderer.java:296) at org.eclipse.e4.workbench.ui.renderers.swt.LazyStackRenderer.processContents(LazyStackRenderer.java:92) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.workbench.ui.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:54) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.workbench.ui.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:54) at org.eclipse.e4.workbench.ui.renderers.swt.WBWRenderer.processContents(WBWRenderer.java:369) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine$4.run(PartRenderingEngine.java:510)
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
IEclipseContext child;
				while (currentActive != trackingContext
						&& (child = (IEclipseContext) currentActive
								.get("activeChild")) != null && child != currentActive) { 
					currentActive = child;
				}
				
				String cssClassName = (currentActive == trackingContext) ? "active" 
						: "inactive"; 
				stylingEngine.setClassname(ctf, cssClassName);
				
				
				if (ctf.getTopRight() != null)
					stylingEngine.setClassname(ctf.getTopRight(), cssClassName);
				
				
				CTabItem[] items = ctf.getItems();
				for (int i = 0; i < items.length; i++) {
					stylingEngine.setClassname(items[i], cssClassName);
				}
			}
		};
		ctf.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent e) {
				updateActiveTab.participating = false;
				folderContext.set(FOLDER_DISPOSED, Boolean.TRUE);
			}
		});
		folderContext.runAndTrack(updateActiveTab);
		return newWidget;