Bug 33389 Read-Only files: Quick fix enabled and gets checkmark!
RC1 1. set a file to ready only. 2. Open the file an set the cursor inside 3. Open the 'Edit' menu. Note that 'Quick fix' is enabled, but 'Content assist' is not 4. Choose 'Quick fix' 5. Open the context menu: Quick fix got a checkmark!
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
/**
	 * Returns the updated java element for the old java element.
	 */
	private IJavaElement findElement(IJavaElement element) {
		
		if (element == null)
			return null;
		
		IWorkingCopyManager manager= JavaPlugin.getDefault().getWorkingCopyManager();
		ICompilationUnit unit= manager.getWorkingCopy(getEditorInput());
		
		if (unit != null) {
			try {
				
				synchronized (unit) {
					unit.reconcile();
				}
				IJavaElement[] findings= unit.findElements(element);
				if (findings != null && findings.length > 0)
					return findings[0];
			
			} catch (JavaModelException x) {
				JavaPlugin.log(x.getStatus());
				
			}
		}
		
		return null;
	}