Anyone pls. let me know how to customize the objects in WebApplication.

Actually i am usign web based java application.

i want to customize some webelement into webbutton.but in object configuration dialog box after selecting the "Web"Environment

Menu-> object idenficication->Select Web Environment

"Usderdefined button" is disabled.

Please tel me is ther any other way to convert webelement into Webbutton.

Also how to use virtual objects in Web Application?