android:minEms is ignored in dialog-themed activities

I have a relatively simple layout that contains an EditText. The activity itself uses the dialog theme. The dialog ends up being tiny, the edit text isn't even big enough to show the initial string.

I know that tiny dialogs are a common problem (IIRC Dianne mentioned that dialogs by default use wrap_content for the parent window), and a typical workaround is to force the dialog to be a certain size in onCreate. I prefer to fix this issue in the layout.

The idea was to give the EditText an android:minEms of 30 to give it a reasonable size (without being ridiculously huge on a tablet), but that seems to be ignored - the EditText (and dialog) is still tiny.

Side note - the dialog's height is too small too - the button at the bottom is half the size it should be.

Layout, for reference:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <TextView android:id="@+id/TextView01"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/title"
        android:gravity="center"
    />
    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
    <ImageButton
        android:id="@+id/file_manager"
        android:src="@drawable/ic_launcher_folder_small"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:onClick="pickFile"
      />
      <EditText android:id="@开发者_JAVA百科+id/file"
            android:text="@string/default_file"
            android:inputType="text"
            android:minEms="30"
            android:layout_toLeftOf="@+id/file_manager"
            android:layout_height="wrap_content"
            android:layout_width="fill_parent"
        />
    </RelativeLayout>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/action"
        android:onClick="performAction"
        android:text="@string/action">
    </Button>
</LinearLayout>

Change your RelativeLayout to android:layout_width="wrap_content".