k-9/res/xml/unread_widget_info.xml

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:initialLayout="@layout/unread_widget_layout"
    android:previewImage="@drawable/preview_unread_widget"
    android:minHeight="60dp"
    android:minWidth="60dp"
    android:configure="com.fsck.k9.activity.UnreadWidgetConfiguration"
    android:updatePeriodMillis="0">
</appwidget-provider>