src/main/java/org/efaps/ui/wicket/behaviors/AjaxDownloadBehavior.java
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