Shows an AlertDialog that doesn't break an active immersive mode. Credits go to Beaver6813 for the original idea (https://stackoverflow.com/questions/22794049/how-do-i-maintain-the-immersive-mode-in-dialogs/23207365)

AlertDialog.kt

/**
 * Creates and shows an [AlertDialog] while maintaining the immersive mode.
 * @param activity the `Activity` which will host the dialog
 * @param title dialog's title
 * @param message dialog's message
 * @param cancelable whether the dialog should be cancelable
 * @param yesButton the text for the positive button (no positive button will be added if `null` is passed)
 * @param noButton the text for the negative button (no negative button will be added if `null` is passed)
 * @param yesCallback callback to invoke when the user presses the positive button
 * @param noCallback callback to invoke when the user presses the negative button
 * @return the dialog
 */
fun showAlertDialog(activity: Activity, title: String, message: String, cancelable: Boolean = true,
                    yesButton: String? = null, noButton: String? = null,
                    yesCallback: (() -> Unit)? = null, noCallback: (() -> Unit)? = null): Dialog {
    val builder = AlertDialog.Builder(activity)
            .setTitle(title)
            .setMessage(message)
            .setCancelable(cancelable)
    yesButton?.let { builder.setPositiveButton(yesButton) { _, _ -> yesCallback?.invoke() } }
    noButton?.let { builder.setNegativeButton(noButton) { _, _ -> noCallback?.invoke() } }
    return builder.create().apply {
        window.setFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE, WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE)
        show()
        window.decorView.systemUiVisibility = activity.window.decorView.systemUiVisibility
        window.clearFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE)
    }
}