Add download example

examples/download.py

@@ -0,0 +1,26 @@
+import io
+from textual import on
+from textual.app import App, ComposeResult
+from textual.binding import Binding
+from textual.widgets import Button
+
+
+class ScreenshotApp(App[None]):
+    BINDINGS = [Binding("s", "deliver_screenshot", "Screenshot")]
+
+    def compose(self) -> ComposeResult:
+        yield Button("Hello, World!")
+
+    @on(Button.Pressed)
+    def on_button_pressed(self) -> None:
+        self.action_deliver_screenshot()
+
+    def action_deliver_screenshot(self) -> None:
+        screenshot_string = self.export_screenshot()
+        string_io = io.StringIO(screenshot_string)
+        self.deliver_text(string_io)
+
+
+app = ScreenshotApp()
+if __name__ == "__main__":
+    app.run()