Bug 306251 MContext's properties needs to actually be populated into the context
Need to fix CPR and then add the code in PRE.
bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/workbench/swt/internal/PartRenderingEngine.java
if (parent instanceof Composite
					&& element.getWidget() instanceof Control) {
				
				final Composite p = (Composite) parent;
				Control c = (Control) element.getWidget();
				if (c.getParent() == parent)
					return c;
				c.setVisible(true);
				c.setLayoutData(null);
				c.setParent(p);
				final Control[] changed = { c };
				
				c.getDisplay().asyncExec(new Runnable() {
					public void run() {
						p.layout(changed, SWT.CHANGED | SWT.DEFER);
						p.getShell().layout(changed, SWT.CHANGED | SWT.DEFER);
					}
				});
				
				if (element instanceof MContext) {
					IEclipseContext ec = ((MContext) element).getContext();
					IEclipseContext pc = getContext(element.getParent());
					ec.set(IContextConstants.PARENT, pc);
				}
				getRendererFor(element.getParent()).childRendered(
						element.getParent(), element);
				return c;
			}
		}