fix focus for windows within a floating frame

Make the `focus` method shift focus to a floating frame. Also, shift
focus away from the floating frame when `focus` is used in an window
within the current main frame.

gui-doc/scribblings/gui/window-intf.scrbl

@@ -65,7 +65,9 @@ If @racket[enable?] is true, the window is enabled, otherwise it is
 @index['("keyboard focus" "setting")]{Moves} the keyboard focus to the
  window, relative to its top-level window, if the window ever accepts
  the keyboard focus.  If the focus is in the window's top-level
- window, then the focus is immediately moved to this
+ window or if the window's top-level window is visible and floating
+ (i.e., created with the @racket['float] style), then the focus is
+ immediately moved to this
  window. Otherwise, the focus is not immediately moved, but when the
  window's top-level window gets the keyboard focus, the focus is
  delegated to this window.

gui-lib/mred/private/wx/cocoa/window.rkt

@@ -761,7 +761,16 @@
                  (is-enabled-to-root?))
         (let ([w (tell cocoa window)])
           (when w
-            (tellv w makeFirstResponder: (get-cocoa-focus))))))
+            (tellv w makeFirstResponder: (get-cocoa-focus))
+            ;; Within a floating frame or when potentially taking
+            ;; focus from a floating frame, also make the frame the
+            ;; key window:
+            (let ([top (get-wx-window)])
+              (when (and (or (send top floating?)
+                             (tell #:type _BOOL w isMainWindow))
+                         (tell #:type _bool w isVisible))
+                (tellv w makeKeyAndOrderFront: #f)))))))
+
     (define/public (on-set-focus) (void))
     (define/public (on-kill-focus) (void))
 

gui-lib/mred/private/wx/gtk/window.rkt

@@ -706,7 +706,15 @@
       (send parent in-floating?))
 
     (define/public (set-focus)
-      (gtk_widget_grab_focus (get-client-gtk)))
+      (define gtk (get-client-gtk))
+      (gtk_widget_grab_focus gtk)
+      ;; Force focus to or away from a floating window:
+      (cond
+       [(and (in-floating?)
+	     (is-shown-to-root?))
+	(gdk_keyboard_grab (widget-window gtk) #t 0)]
+       [else
+	(gdk_keyboard_ungrab 0)]))
 
     (define cursor-handle #f)
     (define/public (set-cursor v)

gui-lib/mred/private/wx/win32/frame.rkt

@@ -428,9 +428,18 @@
       (set! focus-window-path #f)))
   (define/override (set-top-focus win win-path child-hwnd)
     (set! focus-window-path (cons this win-path))
-    (when (ptr-equal? hwnd (GetActiveWindow))
+    (define active-hwnd (GetActiveWindow))
+    (when (or (ptr-equal? hwnd active-hwnd)
+	      (and (or float-without-caption?
+		       (let ([wx (any-hwnd->wx active-hwnd)])
+			 (and wx
+			      (send wx is-floating?))))
+		   (is-shown?)))
       (void (SetFocus child-hwnd))))
 
+  (define/public (is-floating?)
+    float-without-caption?)
+
   (define/private (set-frame-focus)
     (let ([p focus-window-path])
       (when (pair? p)