bootstack.MenuButton#

class bootstack.MenuButton(text='', *, items=None, on_select=None, icon=None, icon_only=False, show_arrow=True, menu_options=None, disabled=False, accent=None, variant='default', density=None, textsignal=None, localize=None, parent=None, **kwargs)#

Bases: IconProperty, PublicWidgetBase

A button that opens a dropdown menu when clicked.

Items are added at construction via items= or dynamically with add_item(). The on_select callback fires for every item click, receiving a dict with type, text, and value keys.

Parameters:

text (str) – Button text. Defaults to an empty string.
items (list[Any] | None) – Initial list of item dicts. Each dict must have a type key ('command', 'check', 'radio', or 'divider') plus item-specific keys such as text, icon, value, and on_click (the per-item callback).
on_select (Callable[[MenuSelectEvent], Any] | None) – Callback fired when any menu item is activated. Called with a MenuSelectEvent (type, text, value of the activated item).
icon (str | IconSpec | None) – Icon name shown on the button face.
icon_only (bool) – If True, hides the label and shows only the icon. Inferred automatically when icon= is set and label is empty. Defaults to False.
show_arrow (bool) – If True (default), shows the dropdown chevron arrow. Pass False to hide it (useful when the icon implies the action).
menu_options (dict[str, Any] | None) – Extra options forwarded to the underlying ContextMenu at construction, using its public parameter names — e.g. {'anchor': 'se', 'offset': (4, 0)}. The menu’s contents, its selection callback, and how it opens belong to the button, so items, command, target, and trigger are not accepted here.
disabled (bool) – If True, button is shown but non-interactive. Defaults to False.
accent (AccentToken | str | None) – Color intent token. Defaults to the theme default.
variant (ButtonVariant) – Style variant. Default 'ghost'.
density (WidgetDensity | None) – Layout density.
textsignal (Signal[str] | None) – Signal[str] bound to the button label text.
localize (LocalizeMode | None) – Whether the button text is translated through the catalog — True, False, or 'auto'. Defaults to the app’s localize_mode.
parent (Any) – Override the context-stack parent widget.
**kwargs (Any) – Layout placement options applied by the parent container — fill, expand, anchor, margin, row, column, sticky. See Arranging Widgets.

property disabled: bool#: Whether the button is non-interactive.

property icon: str | IconSpec | None#

The icon shown on the widget, or None if none is set.

A Bootstrap Icons name, or an IconSpec mapping ({'name', 'size', 'color'}) for control over size and color.

property is_attached: bool#

Whether the widget is currently placed in its layout.

True while the widget occupies space in its parent; False after detach (or before it has ever been placed). A detached widget keeps its state and can be returned to the layout with attach.

property items: list[Any]#: All menu items in insertion order.

property keys: tuple[str, ...]#: Keys of all menu items in insertion order.

property menu: Any#: The underlying ContextMenu — for advanced programmatic access.

property schedule: Schedule#

Scheduler tied to this widget’s lifetime.

All jobs are automatically cancelled when the widget is destroyed. First access creates the Schedule instance; subsequent accesses return the same instance.

Usage:

self.schedule.delay(500, callback)
self.schedule.every(1000, tick)
job = self.schedule.idle(refresh)
job.cancel()

property text: str#

The button’s label text.

Reading reflects a bound textsignal (the option stays synced from the variable). Setting writes through the bound variable when one owns the text — keeping the signal in sync — and falls back to the option otherwise. On an icon-only button the label stays hidden; the setter still updates the underlying text.

add_check_item(label, *, value=False, on_click=None, key=None)#

Add a checkbutton item to the dropdown.

Parameters:

label (str) – Item label text.
value (bool) – Initial checked state.
on_click (Callable[[], Any] | None) – Callback fired on toggle.
key (str | None) – Unique string key. Auto-generated if omitted.

Returns:

The key assigned to this item.

Return type:

str

add_divider(*, key=None)#

Add a horizontal divider to the dropdown.

add_item(label, *, on_click=None, icon=None, shortcut=None, disabled=False, key=None)#

Add a command item to the dropdown.

Parameters:

label (str) – Item label text.
on_click (Callable[[], Any] | None) – Callback fired when the item is clicked.
icon (str | None) – Icon name shown beside the label.
shortcut (str | None) – Keyboard shortcut hint displayed on the right. Accepts a modifier pattern ("Mod+S" → "Ctrl+S" / "⌘S"), a registered shortcut key name, or a literal display string.
disabled (bool) – If True, item is shown but non-interactive.
key (str | None) – Unique string key. Auto-generated if omitted.

Returns:

The key assigned to this item.

Return type:

str

add_items(items)#

Add multiple items at once from a list of item dicts.

Each dict must have a type key plus item-specific keys:

mb.add_items([
    {"type": "command", "text": "Edit",   "icon": "pencil", "on_click": edit},
    {"type": "command", "text": "Delete", "icon": "trash",  "on_click": delete},
    {"type": "divider"},
    {"type": "check",   "text": "Pinned", "value": True},
    {"type": "radio",   "text": "Small",  "value": "sm"},
])

Parameters:: items (list[Any]) – List of item dicts. type accepts 'command', 'check', 'radio', or 'divider'; an item’s on_click key sets its per-item callback.

add_radio_item(label, *, value=None, selected=False, on_click=None, key=None)#

Add a radio-button item to the dropdown.

All radio items in a MenuButton share one group variable automatically. Pass selected=True on the item that should be pre-selected on first open.

Note

Values are stored as strings internally. Pass string values (e.g. value="100%") for predictable comparisons when reading the group selection via menu.

Parameters:

label (str) – Item label text.
value (Any) – Value associated with this radio item. Stored as a string internally; defaults to label when omitted.
selected (bool) – If True, this item is the initial selection. Defaults to False.
on_click (Callable[[], Any] | None) – Callback fired on selection.
key (str | None) – Unique string key. Auto-generated if omitted.

Returns:

The key assigned to this item.

Return type:

str

attach(**kwargs)#

Return a detached widget to its layout, optionally moving it.

With no arguments, restores the widget to exactly where detach took it from. Any layout kwargs accepted by the original placement (e.g. fill, expand, anchor, sticky, margin) override the stored options. For stacked widgets, index= sets the position among the currently attached siblings (or pass an explicit before=/after= sibling); without one, the snapshotted position is used.

Calling attach on a widget that is already attached moves it (the kwargs are re-applied). Fires on_attach.

Parameters:: **kwargs (Any) – Layout placement options to override for this placement.
Raises:: ParentResolutionError – If the widget was never placed in a layout.

capture(path, *, inset=0, settle=0.1)#

Save a picture of this widget to an image file.

Captures the area this widget occupies on screen — one widget, a whole window, or the entire application, depending on what you call it on. The file extension selects the format, so .png, .jpg, and .pdf all work.

The widget has to be visible. A capture reads pixels from the display, so the window is brought to the front first and a hidden or detached widget cannot be captured at all. Any always-on-top setting the window already had is left as it was found.

Pair it with a save dialog to let the user choose where it goes:

import bootstack as bs

def on_export():
    chosen = bs.ask_save_file(initial_file="dashboard.png")
    if chosen:
        app.capture(chosen)

Parameters:

path (str | Path) – Where to write the image. Missing parent folders are created, and the extension chooses the format.
inset (int) – Pixels to trim from every edge, zero or more. Use 2 on a whole window to drop the native border artifact.
settle (float) – Seconds to let the desktop finish repainting before the pixels are read. The default covers the common case of a dialog closing just beforehand. The interface pauses for this long, so a second click on the control that started the capture waits its turn rather than starting an overlapping one.

Returns:

The path that was written.

Raises:

BootstackError – If the widget is not visible on screen or has been scrolled out of view, if inset is negative, if no capture backend is available, or if the file cannot be written.

Return type:

Path

Added in version 0.3.0.

destroy()#

Destroy the widget and release the resources it holds.

Removes the widget from its parent, destroys its children, and cancels any pending or repeating jobs on its schedule. After this the widget must not be used again. Destroying a container destroys everything inside it.

detach()#

Remove the widget from its layout without destroying it.

The widget stops occupying space but keeps its state, children, and event bindings, ready to be returned with attach. The current position is snapshotted so a plain attach() restores it exactly — for stacked siblings this is the index among the currently attached siblings, so detaching other siblings first shifts that index.

Calling detach on a widget that is already detached, or one that was never placed in a layout, does nothing. Fires on_detach.

emit(event, *, data=None)#

Fire a named event on this widget, as if it produced the event itself.

This is how a composite widget surfaces high-level activity to its listeners, and the generic counterpart to the on_*() shorthands for firing events that have no dedicated method.

It is meant for the framework’s own events — 'change', 'select', 'input' and the rest of the data-carrying names. A handler registered through on() or an on_<event>() shorthand receives what is emitted.

Names that map onto a native event instead ('click', 'focus', 'blur', 'submit', …) are a different matter: emitting one asks the toolkit to deliver a real input event, which carries no payload and can reach handlers the widget installed for its own use. Emitting those is not a way to notify listeners, and a listener bound through on() may not see it. Drive the widget through its properties and methods instead.

Parameters:

event (str) – The event name, unprefixed — the same name you pass to on() or an on_<event>() shorthand (e.g. 'change', 'select').
data (Any) – The payload delivered to handlers. Pass the matching payload dataclass from bootstack.events — the same object an on_<event>() handler receives.

Example

from bootstack.events import ChangeEvent

field.emit("change", data=ChangeEvent(value=new_value))

insert_item(index, type, **kwargs)#

Insert a new item at a specific position.

Parameters:

index (int) – Zero-based position to insert at.
type (str) – Item type — 'command', 'check', 'radio', or 'divider'.
**kwargs (Any) – Forwarded to the matching add_* method.

Returns:

The key assigned to the new item.

Return type:

str

item(key)#

Return the item object for key.

Parameters:: key (str) – Key returned by an add_* method.

move_item(key, to_index)#

Move an existing item to a new position.

Parameters:

key (str) – Key of the item to move.
to_index (int) – Target zero-based index.

on(event, handler=None)#

Bind handler to event, or return a composable Stream.

With a handler — binds immediately and returns a Subscription:

sub = widget.on("change", handler)
sub.cancel()

Without a handler — returns a Stream for operator chaining. The Tk binding is created lazily when .listen() is called:

sub = widget.on("change").debounce(300).listen(handler)
sub.cancel()

Parameters:

event (str) – Event name (e.g. "change", "click").
handler (Callable[[Any], Any] | None) – Optional callback. If omitted, a Stream is returned.

Returns:

Subscription when a handler is provided; Stream otherwise.

Return type:

Stream | Subscription

on_attach(handler=None)#

Register a callback fired when the widget enters the layout.

Fires each time the widget becomes visible in its parent — on initial placement and on every attach. Pair it with on_detach to keep per-visibility resources (timers, observers) tied to the widget’s presence on screen. The handler receives a curated Event.

Parameters:: handler (Callable[[Event], Any] | None) – Called when the widget is attached. Omit to get a composable Stream.
Returns:: A cancellable Subscription when a handler is given, otherwise a Stream.
Return type:: Stream | Subscription

on_destroy(handler=None)#

Register a callback fired when the widget is destroyed.

Fires once, as the widget is torn down — the place to release resources the widget owns that aren’t cleaned up automatically (file handles, observers, external subscriptions). The handler receives a curated Event.

Parameters:: handler (Callable[[Event], Any] | None) – Called as the widget is destroyed. Omit to get a composable Stream.
Returns:: A cancellable Subscription when a handler is given, otherwise a Stream.
Return type:: Stream | Subscription

on_detach(handler=None)#

Register a callback fired when the widget leaves the layout.

Fires each time the widget stops occupying space in its parent — on detach and when an ancestor hides it. Pair it with on_attach to release per-visibility resources. The handler receives a curated Event.

Parameters:: handler (Callable[[Event], Any] | None) – Called when the widget is detached. Omit to get a composable Stream.
Returns:: A cancellable Subscription when a handler is given, otherwise a Stream.
Return type:: Stream | Subscription

remove_item(key)#

Remove a dropdown item by key.

Parameters:: key (str) – Key returned by an add_* method.

show_menu()#

Open the dropdown menu programmatically.

Has no effect if the button is disabled or read-only.

update_item(key, **kwargs)#

Reconfigure a dropdown item after creation.

Parameters:

key (str) – Key returned by an add_* method.
**kwargs (Any) – Options forwarded to the item’s configure method.