Skip to content


Tools for lazy loading widgets.

Lazy class

def __init__(self, widget):

Bases: Widget

Wraps a widget so that it is mounted lazily.

Lazy widgets are mounted after the first refresh. This can be used to display some parts of the UI very quickly, followed by the lazy widgets. Technically, this won't make anything faster, but it reduces the time the user sees a blank screen and will make apps feel more responsive.

Making a widget lazy is beneficial for widgets which start out invisible, such as tab panes.

Note that since lazy widgets aren't mounted immediately (by definition), they will not appear in queries for a brief interval until they are mounted. Your code should take this in to account.

def compose(self) -> ComposeResult:
    yield Footer()
    with ColorTabs("Theme Colors", "Named Colors"):
        yield Content(ThemeColorButtons(), ThemeColorsView(), id="theme")
        yield Lazy(NamedColorsView())
Parameter Default Description

A widget that should be mounted after a refresh.