Name

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  LIST_SELECTOR

Purpose

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  The purpose of this function is to implement a pop-up dialog widget
  for the purpose of selecting "names". Names can be names of variables,
  names of files, etc. Any string array can be used.

Calling Sequence

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  selectedNames = List_Selector(theNames)

Arguments

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  theNames: A string array of potential "names" that can be selected.

Keywords

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  ALL: Set this keyword if you wish all the names to be selected
                  initially.
  CANCEL: An output keyword set to 1 if the user cancels or quits the
                  program without hitting the Accept button. Set to 0 if a proper
                  selection was made and the use hits the Accept button.
                   
  COUNT: An output keyword containing the number of elements in the return array.
  GROUP_LEADER: The widget identifier of a widget who will be the group leader
                  for this dialog. Passing a group leader is the *only* way to
                  assure the dialog will be a MODAL dialog (as opposed to a blocking
                  dialog). A GROUP_LEADER is required if you will be using this
                  function in an IDL Virtual Machine application.
                 
  LABEL: A string that will be placed on a label above the selections.
                  If not used, no label is used in the program.
                 
  LIST_COUNTER: If this keyword is set, a number is associated and displayed with
                  each list item, starting with the number 1.
                 
  TITLE: A string that is used for the title of the dialog window. If
                  undefined, then "Selection Widget" is used.
                 
  SELECTED_INDICES: An output vector of the selected indices from theNames array.

Return Value

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  selectedNames: Typically, an array of selected names. If there is only one item
                  in the selection, the variable will be a scalar string.

Example

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  See the List_Selector_Test procedure below. I use the program to allow the
  user to select the names of scientific data sets in an HDF file for further
  reading and processing.

Modification History

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  Written by David W. Fanning, 11 January 2009, based on Name_Selector program.
  Added "Accept on Double-Click" functionality. 14 January 2009. DWF.
  Added LIST_COUNTER keyword. 25 May 2009. DWF.
  Well, basically a RE-DO of yesterday's work, although done correctly today. 26 May 2009. DWF.
  Fixed a problem when the user double-clicks an item in the list. 8 August 2009. DWF.
  Double clicks are a problem with UNIX machines because <CR> sets event.clicks = 2
      prematurely. Removed double-click functionality from all but Windows machines. 9 Feb 2012. DWF.