Bug 28698 Ctrl+O (show outline) does not work if the file being shown in the editor is read only
M4 The summary tells all. Works if the file is not read only. Is this by design?
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
interface ITextConverter {
		void customizeDocumentCommand(IDocument document, DocumentCommand command);
	};
	
	
	class AdaptedRulerLayout extends Layout {
		
		protected int fGap;
		protected AdaptedSourceViewer fAdaptedSourceViewer;
		
		
		protected AdaptedRulerLayout(int gap, AdaptedSourceViewer asv) {
			fGap= gap;
			fAdaptedSourceViewer= asv;
		}
		
		protected Point computeSize(Composite composite, int wHint, int hHint, boolean flushCache) {
			Control[] children= composite.getChildren();
			Point s= children[children.length - 1].computeSize(SWT.DEFAULT, SWT.DEFAULT, flushCache);
			if (fAdaptedSourceViewer.isVerticalRulerVisible())
				s.x += fAdaptedSourceViewer.getVerticalRuler().getWidth() + fGap;
			return s;
		}