Support desktop windowing

Desktop windowing enables users to run multiple apps simultaneously in resizable app windows for a versatile, desktop-like experience.

In figure 1, you can see the organization of the screen with desktop windowing enabled. Things to note:

• Users can run multiple apps side by side simultaneously.
• Taskbar is in a fixed position at the bottom of the display showing the running apps. Users can pin apps for quick access.
• New customizable header bar decorates the top of each window with controls such as minimize and maximize.

By default, apps open full screen on Android tablets. To launch an app in desktop windowing, press and hold the window handle at the top of the screen and drag the handle within the UI, as seen in figure 2.

When an app is open in desktop windowing, other apps open in desktop windows as well.

Users can also invoke desktop windowing from the menu that shows up below the window handle when you tap or click the handle or use the keyboard shortcut Meta key (Windows, Command, or Search) + Ctrl + Down.

Users exit desktop windowing by closing all active windows or by grabbing the window handle at the top of a desktop window and dragging the app to the top of the screen. The Meta + H keyboard shortcut also exits desktop windowing and runs apps full screen again.

To return to desktop windowing, tap or click the desktop space tile in the Recents screen.

Resizability and compatibility mode

In desktop windowing, apps with locked orientation are freely resizable. That means even if an activity is locked to portrait orientation, users can still resize the app to a landscape orientation window.

Apps declared as nonresizable (that is, resizeableActivity = false) have their UI scaled while keeping the same aspect ratio.

Camera apps that lock the orientation or are declared as nonresizable have a special treatment for their camera viewfinders: the window is fully resizable, but the viewfinder keeps the same aspect ratio. By assuming apps always run in portrait or landscape, the apps hardcode or otherwise make assumptions that lead to miscalculations of the preview or captured image orientation or aspect ratio resulting in stretched, sideways, or upside-down images.

Until apps are ready to implement fully responsive camera viewfinders, the special treatment provides a more basic user experience that mitigates the effects wrong assumptions may cause.

To learn more about compatibility mode for camera apps, see Device compatibility mode.

Customizable header insets

All apps running in desktop windowing have a header bar, even in immersive mode. You can customize this bar to prevent your app's content from being obscured and to draw custom UI elements directly into the header space.

Implementation

To draw custom content in the header bar, the first step is to make the header bar background transparent. You can achieve this by using the APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND flag with the WindowInsetsController.

window.insetsController?.setSystemBarsAppearance(
    WindowInsetsController.APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND,
    WindowInsetsController.APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND
)
DesktopWindowing.kt

Once the header bar is transparent, you can style the header area to match your app's design. Use WindowInsets.isCaptionBarVisible to detect if the bar is present and apply the appropriate height or padding to your layout.

@OptIn(ExperimentalLayoutApi::class)
@Composable
fun CaptionBar() {
    if (WindowInsets.isCaptionBarVisible) {
        Row(
            modifier = Modifier
                .windowInsetsTopHeight(WindowInsets.captionBar)
                .fillMaxWidth()
                .background(if (isSystemInDarkTheme()) Color.White else Color.Black),
            horizontalArrangement = Arrangement.Center,
            verticalAlignment = Alignment.CenterVertically
        ) {
            Text(
                text = "Caption Bar Title",
                style = MaterialTheme.typography.titleMedium,
                modifier = Modifier.padding(4.dp)
            )
        }
    }
}
DesktopWindowing.kt

• setSystemBarsAppearance(appearance,mask): Configures the visual style of system bars. The first parameter defines the target appearance flags, while the second acts as a mask to control which specific flags are modified.

• windowInsetsTopHeight(): Automatically sets the height of your Composable to match the system's header bar, helping your custom background fill the caption area without hardcoding pixel values.

• WindowInsets.captionBar: Provides the dimensions for the desktop windowing controls (Close, Maximize, etc.), allowing your UI to scale or hide automatically when entering or leaving desktop windowing.

For more information, see About window insets. In addition to a title, you can display other UI elements in the caption bar, such as tabs—like in Google Chrome—search bars, or profile avatars.

User interface

To avoid overlapping your UI with system buttons, Android 15 provides the WindowInsets#getBoundingRects() method. The method returns a list of Rect objects representing areas occupied by system elements. Any remaining space in the caption bar is a safe zone where you can safely place custom content.

Toggle the appearance of system caption elements for light and dark themes using APPEARANCE_LIGHT_CAPTION_BARS. Access insets using WindowInsets.Companion.captionBar() in Compose, or WindowInsets.Type.captionBar() in Views.

For more information, see About window insets.

Multitasking and multi-instance support

Multitasking is at the core of desktop windowing, and allowing multiple instances of your app can highly increase users productivity.

Android 15 introduces PROPERTY_SUPPORTS_MULTI_INSTANCE_SYSTEM_UI, which apps can set to specify that system UI should be shown for the app to allow it to be launched as multiple instances.

Manage app instances with dragging gestures

In multi-window mode, users can start a new app instance by dragging a view element out of the app's window. Users can also move elements between instances of the same app.

Android 15 introduces two flags to customize drag and drop behavior:

• DRAG_FLAG_START_INTENT_SENDER_ON_UNHANDLED_DRAG: Indicates that an unhandled drag should be delegated to the system to be started if no visible window handles the drop. When using this flag, the caller must provide ClipData with an Item that contains an immutable IntentSender to an activity to be launched (see ClipData.Item.Builder#setIntentSender()). The system can launch the intent or not based on factors like the current screen size or windowing mode. If the system does not launch the intent, the intent is canceled by means of the normal drag and drop flow.

• DRAG_FLAG_GLOBAL_SAME_APPLICATION: Indicates that a drag operation can cross window boundaries (for multiple instances of the same application).

  When startDragAndDrop() is called with this flag set, only visible windows belonging to the same application are able to participate in the drag operation and receive the dragged content.

Additional optimizations

Customize app launches and transition apps from desktop windowing to full screen.

Specify default size and position

Not all apps, even if resizable, need a large window to offer user value. You can use the ActivityOptions#setLaunchBounds() method to specify a default size and position when an activity is launched.

Enter full-screen from the desktop space

Apps can go full-screen by calling Activity#requestFullScreenMode(). The method displays the app full screen directly from desktop windowing.