Bug 29853 [Workbench] OpenWithMenu and setFile
The constructor that only takes the IWorkbenchPage mentions that the user must use the setFile method...this method does not exist.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/OpenWithMenu.java
* <p>
     * If this method is used be sure to set the selected file by invoking
     * <code>setFile</code>.  The file input is required when the user
     * selects an item in the menu.  At that point the menu will attempt to
     * open an editor with the file as its input.
     * </p>
     *
     * @param page the page where the editor is opened if an item within
     *		the menu is selected
     */
    public OpenWithMenu(IWorkbenchPage page) {
        this(page, null);
    }
    /**
     * Constructs a new instance of <code>OpenWithMenu</code>.  
     *
     * @param page the page where the editor is opened if an item within
     *		the menu is selected
     * @param file the selected file
     */
    public OpenWithMenu(IWorkbenchPage page, IAdaptable file) {
        super(ID);
        this.page = page;
        this.file = file;
    }
    /**
     * Returns an image to show for the corresponding editor descriptor.
     *
     * @param editorDesc the editor descriptor, or null for the system editor
     * @return the image or null