<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:id="@+id/layout_root">

    <Spinner
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/alert_dialog_content_margin"
            android:id="@+id/spinner"></Spinner>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:id="@+id/layout_root">

    <Spinner
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/alert_dialog_content_margin"
            android:id="@+id/spinner"></Spinner>
</LinearLayout>

Expand spinner to dialog width.
Expand spinner to dialog width.
