diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/cells-canvas.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/cells-canvas.rkt
new file mode 100644
index 0000000..f24c23b
--- /dev/null
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/cells-canvas.rkt
@@ -0,0 +1,44 @@
+#lang syndicate
+
+;; actor adapter for canvas-double-click% and cells-canvas%
+(require 7GUI/canvas-double-click)
+(require 7GUI/task-7-view)
+(require (only-in "../../widgets.rkt" qc))
+
+(provide spawn-cells-canvas
+         (struct-out single-click)
+         (struct-out double-click)
+         (struct-out update-grid))
+
+(require racket/gui/base
+         (except-in racket/class field))
+
+(message-struct single-click (x y))
+(message-struct double-click (x y))
+(message-struct update-grid (cells))
+
+;; ---------------------------------------------------------------------------------------------------
+(define cells-canvas%
+  (class canvas-double-click%
+    (define/augment-final (on-click x y) (send-ground-message (single-click x y)))
+    (define/augment-final (on-double-click x y) (send-ground-message (double-click x y)))
+    (define *content #f)
+    (define/public (update-grid cells)
+      (set! *content cells)
+      (qc (define dc (send this get-dc))
+          (paint-grid dc *content)))
+    (super-new [paint-callback (lambda (_self dc) (when *content (paint-grid dc *content)))])))
+
+(define (spawn-cells-canvas parent width height)
+  (define parent-component (seal-contents parent))
+  (define canvas (new cells-canvas% [parent parent-component] [style '(hscroll vscroll)]))
+  (qc (send canvas init-auto-scrollbars width height 0. 0.)
+      (send canvas show-scrollbars #t #t))
+
+  (spawn
+   (on (message (update-grid $cells))
+       (qc (send canvas update-grid cells)))
+   (on (message (inbound (single-click $x $y)))
+       (send! (single-click x y)))
+   (on (message (inbound (double-click $x $y)))
+       (send! (double-click x y)))))
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-1.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-1.rkt
index 85609d0..8f78ca7 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-1.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-1.rkt
@@ -19,7 +19,7 @@
      (counter (add1 (counter)))
      (send! (set-text-field view (~a (counter)))))
  (on-start
-  (send! (show-frame frame #t))))))
+  (send! (show frame #t))))))
 
 (module+ main
   (void))
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-2.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-2.rkt
index 68dd5da..e1bb29d 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-2.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-2.rkt
@@ -58,4 +58,4 @@
  (on (message (text-field-update F-field $val))
      (fahrenheit->celsius F-field val))
  (on-start
-  (send! (show-frame frame #t))))))
+  (send! (show frame #t))))))
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-3.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-3.rkt
index d6c0f7d..6780249 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-3.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-3.rkt
@@ -64,6 +64,6 @@
  (on (message (button-press book))
      (displayln "confirmed"))
 
- (on-start (send! (show-frame frame #t))
+ (on-start (send! (show frame #t))
            (enable-return-book (*kind-flight))))
 )
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-4.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-4.rkt
index f097ff8..010eb0e 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-4.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-4.rkt
@@ -57,6 +57,6 @@
  (on (message (slider-update slider $val))
      (duration-cb val))
  (on-start (elapsed-cb)
-           (send! (show-frame frame #t))))
+           (send! (show frame #t))))
 
 )
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-5.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-5.rkt
index 60cbfe3..e9674e3 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-5.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-5.rkt
@@ -69,6 +69,6 @@
 (define (retrieve-name) (string-append (*surname) ", " (*name)))
 
 (on-start (prefix-cb "")
-          (send! (show-frame frame #t))))
+          (send! (show frame #t))))
 
 )
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-6.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-6.rkt
index 52a61ee..16b8cd3 100644
--- a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-6.rkt
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-6.rkt
@@ -202,5 +202,5 @@
 (define canvas (spawn-circle-canvas hpane2 frame undo-but redo-but))
 
 (on (asserted (frame@ frame))
-    (send! (show-frame frame #t)))
+    (send! (show frame #t)))
 )
diff --git a/racket/syndicate-gui-toolbox/examples/7-GUIS/task-7.rkt b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-7.rkt
new file mode 100644
index 0000000..1bba1cd
--- /dev/null
+++ b/racket/syndicate-gui-toolbox/examples/7-GUIS/task-7.rkt
@@ -0,0 +1,96 @@
+#lang syndicate
+
+(require "../../widgets.rkt")
+(require "cells-canvas.rkt")
+(require racket/set racket/list racket/format)
+
+;; a simple spreadsheet (will not check for circularities)
+
+(require 7GUI/task-7-exp)
+(require 7GUI/task-7-view)
+
+;; -----------------------------------------------------------------------------
+(struct formula (formula dependents) #:transparent)
+#; {Formula    =  [formula Exp* || Number || (Setof Ref*)]}
+
+(define (spawn-control frame)
+  (spawn
+   (field [*content  (make-immutable-hash)] ;; [Hashof Ref* Integer]
+          [*formulas (make-immutable-hash)] ;; [Hashof Ref* Formula]
+          )
+
+
+(define-syntax-rule (iff selector e default) (let ([v e]) (if v (selector v) default)))
+(define (get-exp ref*) (iff formula-formula (hash-ref (*formulas) ref* #f) 0))
+(define (get-dep ref*) (iff formula-dependents (hash-ref (*formulas) ref* #f) (set)))
+(define (get-content ref*) (hash-ref (*content) ref* 0))
+
+(local-require 7GUI/should-be-racket)
+(define (set-content! ref* vc)
+  (define current (get-content ref*))
+  (*content (hash-set (*content) ref* vc))
+  (when (and current (not (= current vc)))
+    (when* (get-dep ref*) => propagate-to)))
+
+(define (propagate-to dependents)
+  (for ((d (in-set dependents)))
+    (set-content! d (evaluate (get-exp d) (*content)))))
+
+(define (set-formula! ref* exp*)
+  (define new     (formula exp* (or (get-dep ref*) (set))))
+  (*formulas (hash-set (*formulas) ref* new))
+  (register-with-dependents (depends-on exp*) ref*)
+  (set-content! ref* (evaluate exp* (*content))))
+
+(define (register-with-dependents dependents ref*)
+  (for ((d (in-set dependents)))
+    (*formulas (hash-set (*formulas) d (formula (get-exp d) (set-add (get-dep d) ref*))))))
+
+;; ---------------------------------------------------------------------------------------------------
+;; cells and contents
+(define ((mk-edit title-fmt validator registration source frame) x y)
+  (define cell (list (x->A x) (y->0 y)))
+  (when (and (first cell) (second cell))
+    (react
+     (define value0 (~a (or (source cell) "")))
+     ;; maybe need to make use of queue-callback ?
+     (define dialog (spawn-dialog #:parent #f
+                                  #:style '(close-button)
+                                  #:label (format title-fmt cell)))
+     (define tf (spawn-text-field #:parent dialog
+                                  #:label #f
+                                  #:min-width 200
+                                  #:min-height 80
+                                  #:init-value value0))
+     (on (message (text-field-enter tf $contents))
+         (when* (validator contents)
+                => (lambda (valid)
+                     (stop-current-facet
+                      (send! (show dialog #f))
+                      (registration cell valid)
+                      (send! (update-grid (*content)))))))
+     (on (asserted (dialog@ dialog))
+         (send! (show dialog #t))))))
+
+(define content-edit (mk-edit "content for cell ~a" valid-content set-content! get-content frame))
+
+(define formula-fmt "a formula for cell ~a")
+(define formula-edit (mk-edit formula-fmt string->exp* set-formula! (compose exp*->string get-exp) frame))
+
+;; ---------------------------------------------------------------------------------------------------
+(on (message (single-click $x $y))
+    (content-edit x y))
+(on (message (double-click $x $y))
+    (formula-edit x y))
+(on-start (send! (update-grid (*content))))
+))
+
+;; ---------------------------------------------------------------------------------------------------
+(spawn
+(define frame  (spawn-frame #:label "Cells" #:width (/ WIDTH 2) #:height (/ HEIGHT 3)))
+(define canvas (spawn-cells-canvas frame WIDTH HEIGHT))
+(spawn-control frame)
+
+(on (asserted (frame@ frame))
+    (send! (show frame #t)))
+)
diff --git a/racket/syndicate-gui-toolbox/widgets.rkt b/racket/syndicate-gui-toolbox/widgets.rkt
index fc44717..927b68e 100644
--- a/racket/syndicate-gui-toolbox/widgets.rkt
+++ b/racket/syndicate-gui-toolbox/widgets.rkt
@@ -1,6 +1,9 @@
 #lang syndicate
 
-(provide spawn-frame
+(provide gui-eventspace
+         gui-callback
+         qc
+         spawn-frame
          spawn-horizontal-pane
          spawn-horizontal-panel
          spawn-vertical-pane
@@ -10,8 +13,9 @@
          spawn-gauge
          spawn-slider
          spawn-list-box
+         spawn-dialog
          (struct-out frame@)
-         (struct-out show-frame)
+         (struct-out show)
          (struct-out horizontal-pane@)
          (struct-out horizontal-panel@)
          (struct-out vertical-pane@)
@@ -21,6 +25,7 @@
          (struct-out button-press)
          (struct-out set-text-field-background)
          (struct-out text-field-update)
+         (struct-out text-field-enter)
          (struct-out choice@)
          (struct-out choice-selection)
          (struct-out set-selection)
@@ -34,7 +39,8 @@
          (struct-out set-list-box-choices)
          (struct-out popup-menu)
          (struct-out no-popdown-selected)
-         (struct-out popdown-item-selected))
+         (struct-out popdown-item-selected)
+         (struct-out dialog@))
 
 (require (only-in racket/class
                   new
@@ -42,13 +48,27 @@
                   make-object))
 (require racket/gui/base)
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Eventspace Shennanigans
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define gui-eventspace (make-parameter (make-eventspace)))
+
+(define (gui-callback thnk)
+  (parameterize ([current-eventspace (gui-eventspace)])
+    (queue-callback thnk)))
+
+(define-syntax-rule (qc expr ...)
+  (gui-callback (lambda () expr ...)))
+
+
 ;; an ID is a (Sealof Any)
 ;; an Alignment is a (List (U 'left 'center 'right) (U 'top 'center 'bottom))
 
 (message-struct enable (id val))
 
 (assertion-struct frame@ (id))
-(message-struct show-frame (id value))
+(message-struct show (id value))
 (message-struct popup-menu (parent-id id title x y items))
 (message-struct no-popdown-selected (id))
 (message-struct popdown-item-selected (id item))
@@ -61,6 +81,7 @@
 (message-struct set-text-field (id value))
 (message-struct set-text-field-background (id color))
 (message-struct text-field-update (id value))
+(message-struct text-field-enter (id value))
 
 (assertion-struct button@ (id))
 (message-struct button-press (id))
@@ -79,18 +100,22 @@
 (message-struct list-box-selection (id idx))
 (message-struct set-list-box-choices (id choices))
 
+(assertion-struct dialog@ (id))
+
 (define (enable/disable-handler self my-id)
   (on (message (enable my-id $val))
-      (send self enable val)))
+      (qc (send self enable val))))
 
 ;; String -> ID
 (define (spawn-frame #:label label
-                     #:width [width #f])
+                     #:width [width #f]
+                     #:height [height #f])
   (define frame
-    (parameterize ((current-eventspace (make-eventspace)))
+    (parameterize ((current-eventspace (gui-eventspace)))
       (new frame%
            [label label]
-           [width width])))
+           [width width]
+           [height height])))
   (define id (seal frame))
 
   (define ((on-popdown! pid) self evt)
@@ -101,13 +126,13 @@
 
   (spawn
    (assert (frame@ id))
-   (on (message (show-frame id $val))
-       (send frame show val))
+   (on (message (show id $val))
+       (qc (send frame show val)))
    (on (message (popup-menu id $pid $title $x $y $items))
        (define pm (new popup-menu% [title title] [popdown-callback (on-popdown! pid)]))
        (for ([i (in-list items)])
          (new menu-item% [parent pm] [label i] [callback (popdown-item! pid i)]))
-       (send frame popup-menu pm x y)
+       (qc (send frame popup-menu pm x y))
        (react (stop-when (message (inbound (no-popdown-selected pid))) (send! (no-popdown-selected pid)))
               (stop-when (message (inbound (popdown-item-selected pid $i))) (send! (popdown-item-selected pid i))))))
   id)
@@ -167,11 +192,17 @@
                           #:label label
                           #:init-value init
                           #:enabled [enabled? #t]
-                          #:min-width [min-width #f])
+                          #:min-width [min-width #f]
+                          #:min-height [min-height #f])
   (define parent-component (seal-contents parent))
 
   (define (inject-text-field-update! _ evt)
-    (send-ground-message (text-field-update id (send tf get-value))))
+    (printf "inject-text-field-update!\n")
+    (case (send evt get-event-type)
+      [(text-field)
+       (send-ground-message (text-field-update id (send tf get-value)))]
+      [(text-field-enter)
+       (send-ground-message (text-field-enter id (send tf get-value)))]))
 
   (define tf (new text-field%
                   [parent parent-component]
@@ -179,6 +210,7 @@
                   [init-value init]
                   [enabled enabled?]
                   [min-width min-width]
+                  [min-height min-height]
                   [callback inject-text-field-update!]))
   (define id (seal tf))
 
@@ -187,14 +219,17 @@
    (assert (text-field@ id (val)))
    (enable/disable-handler tf id)
    (on (message (set-text-field id $value))
-       (send tf set-value value)
+       (qc (send tf set-value value))
        (val value))
    (on (message (set-text-field-background id $color))
        (define c (make-object color% color))
-       (send tf set-field-background c))
+       (qc (send tf set-field-background c)))
    (on (message (inbound (text-field-update id $value)))
-       (val (send tf get-value))
-       (send! (text-field-update id (val)))))
+       (val value)
+       (send! (text-field-update id value)))
+   (on (message (inbound (text-field-enter id $value)))
+       (val value)
+       (send! (text-field-enter id value))))
 
   id)
 
@@ -242,7 +277,7 @@
        (selection val)
        (send! (choice-selection id val)))
    (on (message (set-selection id $idx))
-       (send ch set-selection idx)
+       (qc (send ch set-selection idx))
        (selection (send ch get-string-selection))))
 
   id)
@@ -263,7 +298,7 @@
   (spawn
    (assert (gauge@ id))
    (on (message (set-gauge-value id $v))
-       (send g set-value v)))
+       (qc (send g set-value v))))
 
   id)
 
@@ -324,7 +359,30 @@
        (selection val)
        (send! (list-box-selection id val)))
    (on (message (set-list-box-choices id $val))
-       (send lb set val)
+       (qc (send lb set val))
        (selection (get))))
 
   id)
+
+(define (spawn-dialog #:label label
+                      #:parent [parent #f]
+                      #:style [style null])
+  (define parent-component (and parent (seal-contents parent)))
+  (define evt-spc (if parent-component
+                      (send parent-component get-eventspace)
+                      (make-eventspace) #;(gui-eventspace)))
+  (define d (parameterize ((current-eventspace evt-spc))
+              (new dialog%
+                   [label label]
+                   [parent parent-component]
+                   [style style])))
+  (define id (seal d))
+
+  (spawn
+   (assert (dialog@ id))
+
+   (on (message (show id $show?))
+       (qc (send d show show?))
+       (unless show? (stop-current-facet))))
+
+  id)