Tutorial: PlatformProvider.positionOutOfBoundsWindows


Called when a snapshot is being applied and some windows in that snapshot would be fully or partially off-screen. Returns an array of windows with modified positions, such that any off-screen windows are positioned in the top left corner of the main monitor.


const overrideCallback = (PlatformProvider) => {
    class Override extends PlatformProvider {
        async positionOutOfBoundsWindows(
            snapshot, // The snapshot currently being applied
            outOfBoundsWindows // An array of options for all windows that would be fully or partially off-screen. 
        ) {
            // By default, this function cascades out-of-bounds windows from the top left of the main monitor.
            // Perhaps we wish to instead position all such windows on the bottom right.

            // First, find the coordinates of the bottom right of the primary monitor
            const {
                primaryMonitor: {
                    availableRect: { right, bottom }
            } = await fin.System.getMonitorInfo();

            // Update the coordinates of each out-of-bounds window to be bottom right
            const newWindows = snapshot.windows.map((windowOptions) => {
                if (outOfBoundsWindows.find(w => w.name === windowOptions.name)) {
                    // If the window is out of bounds, set a new initial top and left
                    const { defaultHeight, defaultWidth } = windowOptions;
                    return {
                        defaultTop: bottom - defaultHeight,
                        defaultLeft: right - defaultWidth
                } else {
                    return windowOptions;

            // Return all windows with desired bounds
            return newWindows;
    return new Override();

fin.Platform.init({ overrideCallback });