Routines of the Menu File

   NAME : OkFileButtonCallback
   PARAMETERS : int save
                Integer to know what dialog widget call this function.
   RETURN : void
   DESCRIPTION : This is a Callback function that is called when
                 the OK button is selected. It decides if the file
                 is going to be saved, opened or inserted.

   NAME : file_cb
   PARAMETERS : int item_no
                Number of the item menu where this function was called for. 
                Other Parameters not used
   RETURN : void
   DESCRIPTION : This routine creates the FileSelectionDialog widget and
                 this is shared for the option open, save and insert.

   NAME : new_file
   PARAMETERS : void
   RETURN : void
   DESCRIPTION : Set the status of the Main window for a New File
 
   NAME : read_file
   PARAMETERS : char *text
                Name of the file
   RETURN : integer error 
            returns 1 if there are some error messages
   DESCRIPTION : Read the file and put it in the Text Widget
                 Generates an error if the file does not exist
                 or could not read the entire file.

   NAME : save_file
   PARAMETERS : char *filename
                Name of the file
   RETURN : integer error 
            returns 1 if there are some error messages
   DESCRIPTION : Takes the string from the Text Widget and Save it in the
                 given file name
                 If the file does not exist, create a new file

   NAME : insert_file
   PARAMETERS : char *text
                Name of the file
   RETURN : integer error 
            returns 1 if there are some error messages
   DESCRIPTION : Read the file and insert it in the Text Widget in
                 the position where the cursor is.  
                 Generates an error if the file does not exist
                 or could not read the entire file.
   
   NAME : ClearButtonCallBack
   PARAMETERS : Not used
   RETURN : void
   DESCRIPTION : Clear the text window