1. A data processing computer system for customizing a presentation comprising: a bus; a communications unit connected to the bus; a storage device connected to the bus, wherein the storage device stores program code; and a processor unit connected to the bus, wherein the processor unit is configured to run the program code to share a content displayed on a source computer system with a set of target computer systems, wherein the content is displayed on a target display on each target computer system in the set of target computer systems; responsive to a change in the content displayed on the source computer system, identify a progress in displaying the change in the content on the target display on the each target computer system in the set of target computer systems; and generate an indication of the progress in displaying the change in the content on the target display on the each target computer system in the set of target computer systems at the source computer system.