pane

Python bindings for Pane — a modern, minimalist Windows UI engine built on WPF. Build real native Windows app UIs from Python: buttons, checkboxes, sliders, text input, tabs, live light/dark theming and accent-color switching, all with a single custom-chrome window.

The engine itself is C#/WPF; this package drives it in-process via pythonnet, so widgets are the real native controls, not a re-implementation.

Windows only (WPF has no cross-platform equivalent). Requires the free .NET 8 Desktop Runtime — not the SDK, just the runtime.

Install

pip install pane-ui

Quick start

import pane

def build(window):
    window.Content = pane.stack(
        pane.text("Hello from Python", size="title", bold=True),
        pane.button("Click me", style="primary", on_click=lambda: print("clicked!")),
        pane.checkbox("Enable notifications", checked=True),
        spacing=12,
        margin=24,
    )

pane.run(build, title="My App")

Run the full widget gallery from the source repo for a tour of everything available: python examples/gallery.py.

Widgets

button, checkbox, radio_button, toggle_switch, text_box, password_box, progress_bar, slider, combo_box, list_box, nav_list, tab_control, expander, group_box, separator, text, color_swatch, menu_bar, chat_panel, plus set_tooltip / set_context_menu helpers.

combo_box, list_box and nav_list pass the selected item itself to on_change/on_select (not its index) - read .SelectedIndex off the returned control if you need that instead:

pane.combo_box(["Newest first", "Oldest first"], on_change=lambda choice: print(choice))

set_context_menu and menu_bar share the same items format: a list of (label, on_click) pairs, (label, sub_items) pairs for a nested submenu, or None for a separator:

pane.menu_bar([
    ("File", [("New", on_new), ("Open", on_open), None, ("Exit", on_exit)]),
    ("Edit", [("Cut", on_cut), ("Copy", on_copy), ("Paste", on_paste)]),
])

Chat

chat_panel() is a scrollable, bubble-styled message list with an input row - it's just the UI, with no idea what "AI" means:

chat = pane.chat_panel(
    on_send=lambda text: f"you said: {text}",  # return a string for a quick
                                                # synchronous reply, or None
                                                # and call chat.add_message()
                                                # yourself later (e.g. from a
                                                # background thread via
                                                # pane.invoke(), for an LLM
                                                # call that takes real time)
    placeholder="Message...",
    welcome="Hi! What can I help with?",
)
window.Content = pane.stack(chat.control, margin=16)

See examples/chat_app.py for a runnable template - the widget, the input handling, and the recommended async-reply pattern (a background thread + pane.invoke(), so a slow call never freezes the window), with a single placeholder function (get_reply()) marking where you'd wire in a real backend of your choice.

Layout

stack(*children, orientation=, spacing=, margin=), grid(children, rows=, columns=), card(*children), sidebar(*children), scroll(child).

Theming

pane.set_theme("light")        # or "dark"
pane.toggle_theme()
pane.set_accent("#4C82F7")     # hex string or (r, g, b) tuple
pane.reset_accent()

Every widget re-themes live, mid-run, no restart needed.

Events

Callbacks adapt to whatever you write - zero args or one:

pane.button("Save", on_click=lambda: print("saved"))
pane.slider(on_change=lambda value: print(value))

Threading

pane.run(builder) builds the window on a dedicated UI thread and blocks until it's closed. Build your widget tree inside builder. To update the UI later from another thread (a timer, a background task), use pane.invoke(fn) to marshal back onto the UI thread.

License

MIT