tbrowse get class help

I need to set key 28 to OP_NO_HELP in getting field data in tbrowse
class handling. How can I do it in get class. As in reality help in
programming below :


procedure OP_NO_HELP
*------------------------
SELECT 2
go top
private arr[3],secarr[3]
arr[1]:="OPER_NO_"
arr[2]:="op_NA"
arr[3]:="CL_NA"
secarr[1]:="çَِ §ِç «ُàêً‎ُ"
secarr[2]:="©éِ «ُïُِ‎_"
secarr[3]:="©éِ «ُïِ‎ُ"
sc:=savescreen(0,0,24,79)
@ 1,0 to 21,78 double
dbedit (2,1,20,77,arr,"FUN_OP_NO_HELP",,secarr)
restscreen(0,0,24,79,sc)
return

function fun_oP_NO_HELP
do case
case lastkey()=13
C_NO=OPER_NO_
return 0
case lastkey()=27
return 0
otherwise
return 1
endcase