Create a component for the assets pane

using EPiServer.Shell.ViewComposition;

namespace AlloyTemplates.Business {
  [
    Component(
      //Auto-plugs in the component to the assets panel of cms (See EPiServer.Shell.PlugInArea
      //in the EPiServer.UI assembly for Dashboard and CMS constants)
      PlugInAreas = "/episerver/cms/assets",
      Categories = "cms",
      WidgetType = "alloy/components/CustomComponent",
      //Define language path to translate Title/Description.
      //LanguagePath = "/customtranslations/components/customcomponent";
      Title = "My custom component",
      Description = "A custom component that shows information about the current content item."
    )
  ]
  public class CustomComponent {}
}

define([
    // Dojo
    "dojo/_base/declare",
    "dojo/html",
    // Dijit
    "dijit/_TemplatedMixin",
    "dijit/_WidgetBase",
    //CMS
    "epi-cms/_ContentContextMixin"
  ],
  function (
    // Dojo
    declare,
    html,
    // Dijit
    _TemplatedMixin,
    _WidgetBase,
    //CMS
    _ContentContextMixin
  ) {
    return declare([_WidgetBase, _TemplatedMixin, _ContentContextMixin], {
      // summary: A simple widget that listens to changes to the
      // current content item and puts the name in a div.

      templateString: '<div>\
                        <div data-dojo-attach-point="contentName"></div>\
                       </div>',

      postMixInProperties: function () {
        this.getCurrentContent().then(function (context) {
          this._updateUI(context);
        }.bind(this));
      },

      contextChanged: function (context, callerData) {
        this.inherited(arguments);

        // the context changed, probably because we navigated or published something
        this._updateUI(context);
      },

      _updateUI: function (context) {
        html.set(this.contentName, context.name);
      }
    });
  }
);