Workaround:
Toggle the fullscreen mode of the editor by adding the "editor.toggleScreenMode()" method two times at the end of the following callback, located in this JavaScript file ("C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\wpresources\RadEditorSharePoint\7.6.1.0__1f131a624888eeed\Resources\SPEditorTools.js")

configObj.ReturnCallback = function (url, text, config, newAsset) {
    elemLink.href = assetPickerValue.value;
    document.body.removeChild(assetPickerValue);
    if (inserting && url) {
        var images = elemLink.getElementsByTagName("img");
        var textContent = elemLink.innerText != null ? elemLink.innerText : elemLink.textContent;
        if (textContent === "" && (!images || !images.length)) {
            if (linkContent.match(/</)) {
                Telerik.Web.UI.Editor.Utils.setElementInnerHtml(elemLink, linkContent);
            }
            else {
                var textNode = elemLink.ownerDocument.createTextNode(linkContent || text);
                elemLink.appendChild(textNode);
            }
        }
        if (editorSelection) editorSelection.selectRange(currentRange);
        editor.pasteHyperLink(elemLink, "InsertLink");

//WORKAROUND:
        if (editor.isFullScreen() == true) {
            editor.toggleScreenMode();
            editor.toggleScreenMode();
        }
    }
};