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

    <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="?attr/colorPrimary"
                android:elevation="4dp">
        <com.fsck.k9.ui.settings.account.AccountSelectionSpinner
                    android:id="@+id/accountSpinner"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content" />
    </android.support.v7.widget.Toolbar>

    <FrameLayout
            android:id="@+id/accountSettingsContainer"
            android:layout_width="match_parent"
            android:layout_height="0dip"
            android:layout_weight="1"/>

</LinearLayout>

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

    <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="?attr/colorPrimary"
                android:elevation="4dp">
        <com.fsck.k9.ui.settings.account.AccountSelectionSpinner
                    android:id="@+id/accountSpinner"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content" />
    </android.support.v7.widget.Toolbar>

    <FrameLayout
            android:id="@+id/accountSettingsContainer"
            android:layout_width="match_parent"
            android:layout_height="0dip"
            android:layout_weight="1"/>

</LinearLayout>

Use wrap_content in account selection spinner
Use wrap_content in account selection spinner
