Bug 28582 Quickfix icon hides the error icon in editor left ruler [quick fix]
Build 20021216 In presence of problems, one cannot see an error icon in the left ruler, since it get overlapped completely with the quickfix icon. The only error indication is the underlining in the code itself.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
/**
	 * Sets the document provider's save policy.
	 */
	public void setSavePolicy(ISavePolicy savePolicy) {
		fSavePolicy= savePolicy;
	}
	
	/**
	 * Creates a compilation unit from the given file.
	 * 
	 * @param file the file from which to create the compilation unit
	 */
	protected ICompilationUnit createCompilationUnit(IFile file) {
		Object element= JavaCore.create(file);
		if (element instanceof ICompilationUnit)
			return (ICompilationUnit) element;
		return null;
	}
	
	/**
	 * Creates a line tracker working with the same line delimiters as the document
	 * of the given element. Assumes the element to be managed by this document provider.
	 * 
	 * @param element the element serving as blue print
	 * @return a line tracker based on the same line delimiters as the element's document
	 */
	public ILineTracker createLineTracker(Object element) {
		return new DefaultLineTracker();
	}