How to make the documents inserted in a ContentBlock to open in new window?
Is there a way to enable 'open in new window' for document uploaded using Document manager in a Content Block, just like link manager?

1. Create a CustomMediaContentManagerDialog class and inherit the default MediaContentManagerDialog. Add a reference to a custom script file:

using System.Collections.Generic;
using System.Web.UI;
using Telerik.Sitefinity.Web.UI;

namespace SitefinityWebApp
{
    public class CustomMediaContentManagerDialog : MediaContentManagerDialog
    {
        public override IEnumerable<ScriptReference> GetScriptReferences()
        {
            var scripts = new List<ScriptReference>(base.GetScriptReferences());
            scripts.Add(new ScriptReference(CustomMediaContentManagerDialog.ScriptReference, typeof(CustomMediaContentManagerDialog).Assembly.FullName));
            return scripts;
        }
        public static readonly string ScriptReference = "SitefinityWebApp.CustomMediaContentManagerDialog.js";
    }
}

2. Create the custom script and  includes the logic required as below:

_setElementSpecificAttributes: function (jElementToInsert, selectedDataItem) {
...
...
jElementToInsert.attr("target", "_blank");
...
return jElementToInsert;

}

Type.registerNamespace("SitefinityWebApp");

SitefinityWebApp.CustomMediaContentManagerDialog = function (element) {
    SitefinityWebApp.CustomMediaContentManagerDialog.initializeBase(this, [element]);
}

SitefinityWebApp.CustomMediaContentManagerDialog.prototype = {
    

    
    _setElementSpecificAttributes: function (jElementToInsert, selectedDataItem) {
        //TODO: register enum
        var width = null;

        var contentItemSettings = this.get_itemSettingsView().getItemData();

        switch (this.get_dialogMode()) {
            //NotSet                                                                                                                                                                                                                                                                
            case 0:
                throw "Dialog mode not set.";
                break;
                //Image                                                                                                                                                                                                
            case 1:
                var sfref = "";
                var src = "";
                if (contentItemSettings.DisplayMode == "Thumbnail") {
                    sfref = this._getSfrefAttribute('images', selectedDataItem.Id, contentItemSettings.ThumbnailName);
                    src = this._resolveThumbnailUrl(selectedDataItem.ThumbnailUrl, contentItemSettings.ThumbnailName);
                } else {
                    sfref = this._getSfrefAttribute('images', selectedDataItem.Id);
                    src = selectedDataItem.MediaUrl;
                }

                if (contentItemSettings.DisplayMode == "Custom") {
                    var customSizeMethodPropertiesDictionary = contentItemSettings.CustomSizeMethodPropertiesDictionary;
                    customSizeMethodPropertiesDictionary["Method"] = contentItemSettings.Method;
                    var customSizeMethodProperties = Sys.Serialization.JavaScriptSerializer.serialize(customSizeMethodPropertiesDictionary);

                    var requestUrl = String.format(
                        "{0}/custom-image-thumbnail/url?imageId={1}&customUrlParameters={2}&libraryProvider={3}",
                        this.get_thumbnailServiceUrl(),
                        selectedDataItem.Id,
                        customSizeMethodProperties,
                        this.get_provider());

                    jQuery.ajax({
                        type: 'GET',
                        url: requestUrl,
                        processData: false,
                        async: false,
                        contentType: "application/json",
                        success: function (resolvedUrl) {
                            src = resolvedUrl;
                        }
                    });
                }

                var oldSfref = jElementToInsert.attr("sfref");
                var currentImageSfref = sfref;
                jElementToInsert.attr("sfref", sfref);
                jElementToInsert.attr("src", src);

                jElementToInsert.attr("alt", contentItemSettings.AlternateText);
                if (contentItemSettings.Title) jElementToInsert.attr("title", contentItemSettings.Title);

                jElementToInsert.removeAttr("method");
                if (contentItemSettings.Method) jElementToInsert.attr("data-method", contentItemSettings.Method);
                else jElementToInsert.removeAttr("data-method");

                jElementToInsert.removeAttr("customSizeMethodProperties");
                if (contentItemSettings.CustomSizeMethodProperties) jElementToInsert.attr("data-customSizeMethodProperties", contentItemSettings.CustomSizeMethodProperties);
                else jElementToInsert.removeAttr("data-customSizeMethodProperties");

                jElementToInsert.removeAttr("displayMode");
                if (contentItemSettings.DisplayMode) jElementToInsert.attr("data-displayMode", contentItemSettings.DisplayMode);
                else jElementToInsert.removeAttr("data-displayMode");

                jElementToInsert.attr("alt", this.get_altTextField().get_value());
                if (selectedDataItem.Title) jElementToInsert.attr("title", this.get_titleTextField().get_value());

                //Image alignment
                jElementToInsert.css("float", "");
                jElementToInsert.css("vertical-align", "");
                switch (contentItemSettings.Alignment) {
                    case "Left":
                        jElementToInsert.css("float", "left");
                        break;
                    case "Right":
                        jElementToInsert.css("float", "right");
                        break;
                    case "Center":
                        jElementToInsert.css("vertical-align", "middle");
                        break;
                    default:
                        break;
                }

                this._domElementToInsert.style.margin = "";
                if (contentItemSettings.MarginTop != null)
                    this._domElementToInsert.style.marginTop = contentItemSettings.MarginTop + "px";
                
                if (contentItemSettings.MarginBottom != null)
                    this._domElementToInsert.style.marginBottom = contentItemSettings.MarginBottom + "px";
                if (contentItemSettings.MarginLeft != null)
                    this._domElementToInsert.style.marginLeft = contentItemSettings.MarginLeft + "px";
                if (contentItemSettings.MarginRight != null)
                    this._domElementToInsert.style.marginRight = contentItemSettings.MarginRight + "px";

                var oldOpenOriginalImageOnClick = jElementToInsert.attr("openOriginalImageOnClick") || jElementToInsert.attr("data-openOriginalImageOnClick");
                jElementToInsert.removeAttr("openOriginalImageOnClick");

                if (contentItemSettings.OpenOriginalImageOnClick) {
                    jElementToInsert.attr("data-openOriginalImageOnClick", "true");
                } else if (jElementToInsert.attr("data-openOriginalImageOnClick")) {
                    jElementToInsert.removeAttr("data-openOriginalImageOnClick");
                }

                // We check if the image is wrapped in an anchor tag, we check if this anchor tag is related to the image and we update its 
                // sfref attribute if needed
                var imageLinkSfref = this._getImageOpenOriginalLink(jElementToInsert);
                var isWrappingLinkImpacted = (imageLinkSfref && oldOpenOriginalImageOnClick);
                if (isWrappingLinkImpacted) {
                    var jWrappingLink = jElementToInsert.parent();
                    var newOriginalImageSfref = this._getSfrefAttribute('images', selectedDataItem.Id);
                    jWrappingLink.attr("sfref", newOriginalImageSfref);
                }


                // If there is no wrapping anchor tag and we need to create one, we first remove the wrapping image span - this way we avoid the RadEditor
                // related problems.
                if (!imageLinkSfref && contentItemSettings.OpenOriginalImageOnClick) {
                    var originalImageSfref = this._getSfrefAttribute('images', selectedDataItem.Id);
                    jElementToInsert.wrap("<a></a>");
                    jElementToInsert = jElementToInsert.parent();
                    jElementToInsert.attr("sfref", originalImageSfref).attr("href", selectedDataItem.MediaUrl);
                }

                break;
                //Document                                                                                                                                                                                                                                                                
            case 2:
                jElementToInsert.attr("sfref", this._getSfrefAttribute('documents', selectedDataItem.Id));
                jElementToInsert.attr("href", selectedDataItem.MediaUrl);
                jElementToInsert.attr("target", "_blank");
                var title = null;
                var html = null;

                if (jElementToInsert.children().length > 0) {
                    html = jElementToInsert.html();
                }
                else {
                    title = this.get_titleTextField().get_value();
                    if (title === "")
                        title = jElementToInsert.html();
                    if (title === "")
                        title = selectedDataItem.Title;

                    html = title;
                }

                if (title)
                    jElementToInsert.attr("title", title);

                var showText = true;
                if (jElementToInsert.children().length > 0) {
                    var childElement = jElementToInsert.children().get(0);
                    var tagName = (childElement && childElement.tagName) ? childElement.tagName : "";
                    if (tagName == "IMG") {
                        showText = false;
                    }
                }

                if (showText) {
                    jElementToInsert.html(html);
                }
                break;
                //Media                                                                                                                                                                                                                                                                
            case 3:
                width = contentItemSettings.ResizedWidth ? contentItemSettings.ResizedWidth : 150;

                var objectElement = this._createObjectElement(this._getSfrefAttribute('videos', selectedDataItem.Id), selectedDataItem.MediaUrl, width);
                jElementToInsert.html(objectElement);
                break;
            default:
                throw "Not supported.";
        }
        return jElementToInsert;
    }
  
}
SitefinityWebApp.CustomMediaContentManagerDialog.registerClass('SitefinityWebApp.CustomMediaContentManagerDialog', Telerik.Sitefinity.Web.UI.MediaContentManagerDialog);

3. Register the custom dialog in the Global.asax file:

protected void Application_Start(object sender, EventArgs e)
{
	Bootstrapper.Initialized += this.Bootstrapper_Initialized;
}

private void Bootstrapper_Initialized(object sender, Telerik.Sitefinity.Data.ExecutedEventArgs e)
{
	if (e.CommandName == "Bootstrapped")
	{
		ObjectFactory.Container.RegisterType(typeof(DialogBase), typeof(CustomMediaContentManagerDialog), typeof(MediaContentManagerDialog).Name, new HttpRequestLifetimeManager());
	}
}