implement get-focus-window' and get-edit-target-window' in back end to avoid relying on `on-focus' callback handling

collects/mred/private/wx/cocoa/frame.rkt

@@ -379,6 +379,13 @@
         (when is-main?
           (do-notify-responder wx on?))))
 
+    (define/public (get-focus-window [even-if-not-active? #f])
+      (let ([f-cocoa (tell cocoa firstResponder)])
+        (and f-cocoa
+             (or even-if-not-active?
+                 (tell #:type _BOOL cocoa isKeyWindow))
+             (->wx (get-ivar f-cocoa wxb)))))
+
     (define/public (install-wait-cursor)
       (when (positive? (eventspace-wait-cursor-count (get-eventspace)))
         (tellv (get-wait-cursor-handle) set)))

collects/mred/private/wx/gtk/frame.rkt

@@ -49,6 +49,7 @@
 (define-gtk gtk_window_set_gravity (_fun _GtkWindow _int -> _void))
 (define-gtk gtk_window_set_icon_list (_fun _GtkWindow _GList -> _void))
 (define-gtk gtk_window_fullscreen (_fun _GtkWindow -> _void))
+(define-gtk gtk_window_get_focus (_fun _GtkWindow -> _GtkWidget))
 
 (define-gtk gtk_window_resize (_fun _GtkWidget _int _int -> _void))
 
@@ -376,6 +377,14 @@
 				(unless (eq? on? reported-activate)
 				  (set! reported-activate on?)
 				  (on-activate on?)))))))
+
+    (define/public (get-focus-window [even-if-not-active? #f])
+      (let ([f-gtk (gtk_window_get_focus gtk)])
+        (and f-gtk
+             (or even-if-not-active?
+                 (positive? (bitwise-and (get-gtk-object-flags f-gtk)
+                                         GTK_HAS_FOCUS)))
+             (gtk->wx f-gtk))))
     
     (define/override (call-pre-on-event w e)
       (pre-on-event w e))

collects/mred/private/wx/win32/frame.rkt

@@ -296,6 +296,12 @@
     (when (pair? focus-window-path)
       (SetFocus (send (last focus-window-path) get-focus-hwnd))))
 
+  (define/public (get-focus-window [even-if-not-active? #f])
+    (and focus-window-path
+         (or even-if-not-active?
+             (ptr-equal? hwnd (GetActiveWindow)))
+         (last focus-window-path)))
+
   (define/override (can-accept-focus?)
     #f)
   (define/override (child-can-accept-focus?)

collects/mred/private/wx/win32/window.rkt

@@ -143,6 +143,7 @@
         0
         (cond
          [(= msg WM_SETFOCUS)
+          (set-top-focus this null w)
           (queue-window-event this (lambda () (on-set-focus)))
           0]
          [(= msg WM_KILLFOCUS)

collects/mred/private/wxtop.rkt

@@ -70,7 +70,7 @@
     (class100 (wx-make-container% (wx-make-window% base% #t)) (parent . args)
       (inherit get-x get-y get-width get-height set-size
 	       get-client-size is-shown? on-close enforce-size
-               get-eventspace)
+               get-eventspace get-focus-window)
       (private-field
        ;; have we had any redraw requests while the window has been
        ;; hidden?
@@ -94,7 +94,6 @@
        
        [enabled? #t]
        [focus #f]
-       [target #f]
 
        [border-buttons null]
 
@@ -132,21 +131,17 @@
 							  (eq? b w))))))
 			     border-buttons)
 		   (when (w . is-a? . wx:button%)
-		     (send w defaulting #t)))))
+		     (send w defaulting #t))))
-	   (set! focus w)
+             (set! focus w)))]
-	   (when w
-	     (set! target w)))]
 	
-	[get-focus-window
-	 (lambda () focus)]
 	[get-edit-target-window
-	 (lambda () (and target (send (wx->proxy target) is-shown?) target))]
+	 (lambda () (get-focus-window #t))]
 	[get-focus-object
 	 (lambda ()
-	   (window->focus-object focus))]
+	   (window->focus-object (get-focus-window)))]
 	[get-edit-target-object
 	 (lambda ()
-	   (window->focus-object target))]
+	   (window->focus-object (get-focus-window #t)))]
 
 	[window->focus-object
 	 (lambda (w)