[jdt-ui-dev] How to implement content assistant for function's parameter

["" <liwenlong@xxxxxxxxxxxxxxx>]

Now I try to implement content assist for function's parameter. I have defined 
several functions as well as their parameters. I put a sourcviewer and serveral
buttons in a dialog.When I press one button,There is a list of function
computation proposals,that is I have implement the function proposal,but when I
input one function through double-click one proposal,the function's parameter can
not be shown after the character "(".For example, if I input the concat()
function,I hope the parameter for concat() can be show after "(" position until
the cursor passes the ")".

   I don't know how to implment this function, can you give me some advice or
example,thx in advance