1. A system comprising: one or more processors; and memory having program instructions stored thereon that are capable of causing the one or more processors to implement a cloud-based application that is operable to perform operations including: maintaining indications of a plurality of widgets based on one or more data objects stored in one or more databases accessible to the cloud-based application, wherein the plurality of widgets are capable of being displayed via a client device, and wherein a displayed widget is operable to: receive information indicative of user input via the client device; and communicate with the cloud-based application and with one or more others of the plurality of widgets; causing at least a first one of the plurality of widgets and a second one of the plurality of widgets to be displayed via the client device, wherein the first widget is associated with a first domain, and the second widget is associated with a second domain, wherein the first domain is different from the second domain; processing a first message received at the second domain from the first domain, wherein the first message identifies one or more functions to be performed by or in relation to the second widget; and sending a second, different message from the second domain to the first domain, wherein the second message identifies an occurrence event indicating that the one or more functions have been performed, wherein the one or more functions are performed in response to one or more user actions, wherein the second message is capable of being processed to cause one or more callback functions to be invoked with respect to the one or more functions, and wherein execution of the one or more callback functions causes data associated with the first widget to be updated.