A customer is running graphic applications on a Citrix server displaying the results on a Citrix client connected over a slow modem line. This is usually quite fast because Citrix is designed to only update the part of a graphics window that has changed, not the whole window.
When running Java applications, the whole window is always repainted even if only a small part of the window has been updated. This causes extensive delays when run on a Citrix server and displaying on a Citrix client. The delay is often so long that many people feels it's more or less useless to run Java applications this way.
The customer wants Java to only display the updated the parts of a graphics widow and thereby increase the performance of applications that uses Java graphics.