gtags search buffter

[liangbo]

target program: C language
SourceCodeTag: gtags

when using command of 'M-x gtags-find-rtag',
the following four columns messages were displayed on search buffer.
.Tag Name
.LineNo.
.Files Name
.contents

My question is how to add one more column such as Funcation's Name?

For example:
change before:(*GTAGS SELECT*(CONTEXT)AAAA)
  AAAA  101  src/foo.c  case AAAA:
  AAAA  78   src/oof.c  i = AAAA:
change after:
  AAAA  101  src/foo.c  case AAAA:   test()
  AAAA  78   src/oof.c  i = AAAA:    main()