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Window

This class is meant to be used as a property of Page.window.

All properties and methods of the Window class are available only on Desktop 🖥️ platforms.

Window class has the following properties:

alignment​

Defines the alignment of the app window.

Value is of type Alignment.

always_on_bottom​

Whether the app window should always be displayed below other windows.

Defaults to False.

Has effect on Linux and Windows only.

always_on_top​

Whether the app window should always be displayed on top of other windows.

Defaults to False.

badge_label​

Sets a badge label on the app window.

Has effect on macOS only.

bgcolor​

Sets background color of an application window.

Use together with page.bgcolor to make a window transparent:

import flet as ft

def main(page: ft.Page):
    page.window.bgcolor = ft.colors.TRANSPARENT
    page.bgcolor = ft.colors.TRANSPARENT
    page.window.title_bar_hidden = True
    page.window.frameless = True
    page.window.left = 400
    page.window.top = 200
    page.add(ft.ElevatedButton("I'm a floating button!"))

ft.app(main)

focused​

Set to True to focus a native OS window.

frameless​

Whether the app window should be frameless.

full_screen​

Whether to switch app's native OS window to a fullscreen mode.

Defaults to False.

height​

Defines the height of the app window.

icon​

Sets the icon of the app window.

Has effect on Windows only.

left​

Defines the horizontal position of the app window - a distance in virtual pixels from the left edge of the screen.

maximizable​

Whether to hide/disable native OS window's "Maximize" button.

Defaults to True.

maximized​

Whether the app window containing is maximized. Set this property to True to programmatically maximize the window and set it to False to unmaximize it.

max_height​

Defines the maximum height of the app window.

max_width​

Defines the maximum width of the app window.

minimizable​

Whether the app window can be minimized through the window's "Minimize" button.

Defaults to True.

minimized​

Whether the app window is minimized. Set this property to True to programmatically minimize the window and set it to False to restore it.

min_height​

Defines the minimum height of the app window.

min_width​

Defines the minimum width of the app window.

movable​

Whether the app window can be moved.

Defaults to True.

Has effect on macOS only.

opacity​

Defines the opacity of a native OS window.

Value must be between 0.0 (fully transparent) and 1.0 (fully opaque).

resizable​

Whether the app window can be resized.

Defaults to True.

shadow​

Whether to display a shadow around the app window.

On Windows, doesn't do anything unless window is frameless.

Has effect on macOS and Windows only.

title_bar_hidden​

Whether to hide the app window's title bar.

See WindowDragArea control that allows moving an app window with hidden title bar.

title_bar_buttons_hidden​

Whether to hide the app window's title bar buttons.

Has effect on macOS only.

top​

Defines the vertical position of a native OS window - a distance in virtual pixels from the top edge of the screen.

prevent_close​

Set to True to intercept the native close signal. Could be used together with page.window.on_event() event handler and page.window-destroy() to implement app exit confirmation logic - see page.window.destroy() for code example.

progress_bar​

The value from 0.0 to 1.0 to display a progress bar on Task Bar (Windows) or Dock (macOS) application button.

Has effect on Windows and macOS only.

skip_task_bar​

Set to True to hide application from the Task Bar (Windows) or Dock (macOS).

visible​

Whether to make the app window visible. Used when the app is starting with a hidden window.

The following program starts with a hidden window and makes it visible in 3 seconds:

from time import sleep

import flet as ft

def main(page: ft.Page):
    page.add(ft.Text("Hello!"))

    sleep(3)
    
    page.window.visible = True
    page.update()  

ft.app(main, view=ft.AppView.FLET_APP_HIDDEN)

Note view=ft.AppView.FLET_APP_HIDDEN which hides app window on start.

width​

Defines the width of the app window.

Methods​

center()​

Move app window to the center of the screen.

close()​

Closes app window.

destroy()​

Forces closing app window.

This method could be used with page.window.prevent_close = True to implement app exit confirmation:

import flet as ft

def main(page: ft.Page):
    page.title = "MyApp"

    def handle_window_event(e):
        if e.data == "close":
            page.open(confirm_dialog)

    page.window.prevent_close = True
    page.window.on_event = handle_window_event

    def yes_click(e):
        page.window.destroy()

    def no_click(e):
        page.close(confirm_dialog)

    confirm_dialog = ft.AlertDialog(
        modal=True,
        title=ft.Text("Please confirm"),
        content=ft.Text("Do you really want to exit this app?"),
        actions=[
            ft.ElevatedButton("Yes", on_click=yes_click),
            ft.OutlinedButton("No", on_click=no_click),
        ],
        actions_alignment=ft.MainAxisAlignment.END,
    )

    page.add(ft.Text('Try exiting this app by clicking window\'s "Close" button!'))

ft.app(main)

to_front()​

Brings app window to the foreground (on top of other windows).

Events​

on_event​

Fires when app window changes its state: position, size, maximized, minimized, etc.

Event handler argument is of type WindowEvent.