Bug 16181 Tab key doesn't work in editor when 'Insert spaces for tabs' enabled
Using integration build 0515, pressing Tab in an editor window doesn't do anything when 'Insert spaces for tabs' is selected. The editor is marked as unsaved, but no spaces appear.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
public void addTextConverter(ITextConverter textConverter) {
			if (fTextConverters == null) {
				fTextConverters= new ArrayList(1);
				fTextConverters.add(textConverter);
			} else if (!fTextConverters.contains(textConverter))
				fTextConverters.add(textConverter);
		}
		
		public void removeTextConverter(ITextConverter textConverter) {
			if (fTextConverters != null) {
				fTextConverters.remove(textConverter);
				if (fTextConverters.size() == 0)
					fTextConverters= null;
			}
		}
		
		/*
		 * @see TextViewer#customizeDocumentCommand(DocumentCommand)
		 */
		protected void customizeDocumentCommand(DocumentCommand command) {
			super.customizeDocumentCommand(command);
			if (fTextConverters != null) {
				for (Iterator e = fTextConverters.iterator(); e.hasNext();)
					((ITextConverter) e.next()).customizeDocumentCommand(getDocument(), command);
			}
		}
		
		public IVerticalRuler getVerticalRuler() {
			return fCachedVerticalRuler;
		}