;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
;+
; NAME: findtopid
;
; PURPOSE: retrouve a partir d''un Id de widget l'Id du widget qui est
; "the top-level base" (i.e., it has no parent)
;
; CATEGORY: aide pour les widgets
;
; CALLING SEQUENCE: res=findtopid(Widget_ID)
; 
; INPUTS: Widget_ID: this argument should be the widget ID of the
; widget for which information is desired.
;
; KEYWORD PARAMETERS:
;
; OUTPUTS: l'Id du widget qui est "the top-level base"
;
; COMMON BLOCKS:
;
; SIDE EFFECTS: 
;
; RESTRICTIONS:
;
; EXAMPLE:
;
; MODIFICATION HISTORY:Sebastien Masson (smasson@lodyc.jussieu.fr)
;                      22/9/1999
;-
;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
FUNCTION findtopid,  identite
;
  compile_opt idl2, strictarrsubs
;
   id = long(identite)
;    exist = widget_info(id, /managed)
;    if exist EQ 0 then return,  -1
   topid = id
   topid2 = id
   while topid2 NE 0 do begin
      topid = topid2
      topid2 = widget_info(topid2, /parent)
   endwhile
   return,  long(topid)
end