fix regression with dialog windows refusing to close

pd/nw/dialog_canvas.html

@@ -754,7 +754,7 @@ function add_events(name) {
         //pdgui.pdsend(name + " menuclose 0");
         //cancel();
         pdgui.remove_dialogwin(pd_object_callback);
-        this.close(true);
+        gui.Window.get().close(true);
     });
     pdgui.dialog_bindings(name);
 }

pd/nw/dialog_font.html

@@ -186,7 +186,7 @@ function add_events(name) {
         //pdgui.pdsend(name, "menuclose 0");
         //cancel();
         pdgui.remove_dialogwin(pd_object_callback);
-        this.close(true);
+        gui.Window.get().close(true);
     });
     pdgui.dialog_bindings(name);
 }

pd/nw/dialog_gatom.html

@@ -275,7 +275,7 @@ function add_events(name) {
         //pdgui.pdsend(name, "menuclose 0");
         //cancel();
         pdgui.remove_dialogwin(pd_object_callback);
-        this.close(true);
+        gui.Window.get().close(true);
     });
     pdgui.dialog_bindings(name);
 }

pd/nw/dialog_iemgui.html

@@ -559,7 +559,7 @@ function add_events(name) {
         //pdgui.pdsend(name, "menuclose 0");
         //cancel();
         pdgui.remove_dialogwin(pd_object_callback);
-        this.close(true);
+        gui.Window.get().close(true);
     });
     pdgui.dialog_bindings(name);
 }

pd/nw/dialog_prefs.html

@@ -634,7 +634,7 @@ function add_events(name) {
     gui.Window.get().on("close", function() {
         // this needs to do whatever the "cancel" button does
         pdgui.remove_dialogwin(pd_object_callback);
-        this.close(true);
+        gui.Window.get().close(true);
     });
     pdgui.dialog_bindings(name);
 }