protected CharSequence getCallBackScript(final String _url)
    {
        final StringBuilder js = new StringBuilder()
            .append("baseWindow.withDoc(top.dojo.doc, function () {\n")
            .append("var node = dom.byId('downloadFrame');\n")
            .append("if (node == null) {\n")
            .append("node = domConstruct.place('<iframe id=\"downloadFrame\" src=\"about:blank\" ")
                .append("style=\"position: absolute; left: 1px; top: 1px; height: 1px; width: 1px; ")
                .append("visibility: hidden\">', win.body());\n")
            .append("}\n")
            .append("node.src='").append(_url).append("';")
            .append("});\n");
        return DojoWrapper.require(js, DojoClasses.baseWindow, DojoClasses.dom, DojoClasses.domConstruct);
    }
protected CharSequence getCallBackScript(final String _url)
    {
        final StringBuilder js = new StringBuilder()
            .append("baseWindow.withDoc(top.dojo.doc, function () {\n")
            .append("var node = dom.byId('downloadFrame');\n")
            .append("if (node == null) {\n")
            .append("node = domConstruct.place('<iframe id=\"downloadFrame\" src=\"about:blank\" ")
                .append("style=\"position: absolute; left: 1px; top: 1px; height: 1px; width: 1px; ")
                .append("visibility: hidden\">', win.body());\n")
            .append("}\n")
            .append("node.src='").append(_url).append("';")
            .append("});\n");
        return DojoWrapper.require(js, DojoClasses.baseWindow, DojoClasses.dom, DojoClasses.domConstruct);
    }
protected CharSequence getCallBackScript ( final String _url ) { final StringBuilder js = new StringBuilder ( ) . append ( "baseWindow.withDoc(top.dojo.doc, function () {\n" ) . append ( "var node = dom.byId('downloadFrame');\n" ) . append ( "if (node == null) {\n" ) . append ( "node = domConstruct.place('<iframe id=\"downloadFrame\" src=\"about:blank\" " ) . append ( "style=\"position: absolute; left: 1px; top: 1px; height: 1px; width: 1px; " ) . append ( "visibility: hidden\">', win.body());\n" ) . append ( "}\n" ) . append ( "node.src='" ) . append ( _url ) . append ( "';" ) . append ( "});\n" ) ; return DojoWrapper . require ( js , DojoClasses . baseWindow , DojoClasses . dom , DojoClasses . domConstruct ) ; }
Script that searches for an existing iframe to use it for the download of the frame.
If it does not exist it will be created.

@param _url the url
@return the callback script
Script that searches for an existing iframe to use it for the download of the frame . If it does not exist it will be created .