diff --git a/nionui_app/nionui_examples/ui_demo/Dialog.py b/nionui_app/nionui_examples/ui_demo/Dialog.py
new file mode 100644
index 0000000..227b5ef
--- /dev/null
+++ b/nionui_app/nionui_examples/ui_demo/Dialog.py
@@ -0,0 +1,67 @@
+# standard libraries
+import gettext
+import typing
+
+
+# third party libraries
+# None
+
+# local libraries
+from nion.ui import Declarative
+from nion.swift import Facade
+
+if typing.TYPE_CHECKING:
+    from nion.ui import UserInterface
+
+dialog_open = False
+
+api: Facade.API_1 = Facade.get_api("~1.0", "~1.0")
+
+_ = gettext.gettext
+
+
+# user program below
+
+class Handler(Declarative.Handler):
+    def __init__(self) -> None:
+        super().__init__()
+        self.label_item_lb: typing.Optional[UserInterface.LabelWidget] = None
+        self.click_count = 0
+        self.on_closed: typing.Optional[typing.Callable] = None
+
+    def button_clicked(self, widget: Declarative.UIWidget) -> None:
+        assert self.label_item_lb
+        self.click_count += 1
+        self.label_item_lb.text = _("Clicked") + " " + str(self.click_count)
+
+    def close(self) -> None:
+        if callable(self.on_closed):
+            self.on_closed()
+        super().close()
+
+
+class View():
+    def __init__(self):
+        ui = Declarative.DeclarativeUI()
+        self.label_item = ui.create_label(text="", name="label_item_lb")
+        self.click_count = ui.create_push_button(text="Click", name = "click_count_pb",on_clicked="button_clicked")
+        self.ui_view: Declarative.UIDescription = ui.create_column(self.click_count,self.label_item)
+
+def open_dialog() -> None:
+    global dialog_open
+    if not dialog_open:
+        ui = Declarative.DeclarativeUI()
+        document_controller = api.application.document_controllers[0]._document_controller
+        ui_handler = Handler()
+        ui_view = View().ui_view
+        def dialog_closed():
+            print("close")
+            global dialog_open
+            dialog_open = False
+        # note that a more straightforward way would be to directly put the dialog_closed
+        # code into the close methode of the handler
+        ui_handler.on_closed = dialog_closed
+        ui_view = ui.create_modeless_dialog(ui_view,title="Clicker",)
+        dialog: Declarative.Dialog = Declarative.construct(document_controller.ui, document_controller, ui_view, ui_handler,[dialog_closed])
+        dialog.show()
+        dialog_open = True
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