(define (script-fu-set-layers-average-opacity image layer 
            
         )
	
		(let* 
		   (
		   (width (car (gimp-image-width image)))
		   (height (car (gimp-image-height image)))
		   (count 0)
		   (text-layer 0)
		   (layer-width 0)
		   (layer-height 0)
		   (x 0)
		   (y 0)
		   (layer-count 0)
		   (layer-counter 0)
		   (layers 0)
		   (layer1 0)
		   (layer-name 0)
		   (nlayer 0)
		   )
			;(gimp-image-undo-disable image); DN = NO UNDO
			(gimp-context-push)
			(gimp-image-undo-group-start image)                   ;undo-group in one step
			
			
			(set! layer-count (car (gimp-image-get-layers image)))
			(set! layers (cadr (gimp-image-get-layers image)))
			;make all layers same opacity as entered by user
			(set! nlayer layer-count)
			(set! layer-counter 0)
			(while (< layer-counter layer-count)
				(set! layer1 (vector-ref layers layer-counter))
				(gimp-layer-set-opacity layer1 (/ 100 nlayer))
				(set! nlayer (- nlayer 1))
				(set! layer-counter (+ layer-counter 1))
			)
			
		   ;(gimp-image-undo-enable image) ;DN = NO UNDO
			(gimp-image-undo-group-end image)                     ;undo group in one step
			(gimp-context-pop)
			(gimp-displays-flush)
	    )
	
	
    
) ;end of define
(script-fu-register
  "script-fu-set-layers-average-opacity"         ;function name
  "<Image>/Script-Fu/Set All Layers Average Opacity"    ;menu register
  "Set All layers average opacity where n-th layer is set to 1/N opacity"       ;description
  "Tin Tran"                          ;author name
  "copyright info and description"         ;copyright info or description
  "2016"                          ;date
  "RGB*, GRAY*"                        ;mode
  SF-IMAGE      "Image" 0                   
  SF-DRAWABLE   "Layer" 0
  ;SF-ADJUSTMENT "Set Opacity" '(50.0 0.0 100.0 1.0 10.0 1 1)
)