Hello,I want to know about the click event of the message form SEND button.So I want to add few code and made changes in SEND button click event.Please tell me about the event name and file.thanks

I want to add 2-3 addition fields for the searching contact in SearchUser.ascx.Currently user is filter by usernam which is display in drop down, In that drop down box I want to add field1 and field2 on that field  I want to customize the searching operation.For that I want to know two points of code,1. From where query is execute in code for ...