I'm trying to create a Custom Dialog like this, I'm following this answer but changing the layout_gravity to this android:layout_gravity="center_horizontal|top" and it puts on the center of the Dialog as I want, but the thing is that if I want to put the ImageView bigger it destroys the xml, also the Dialog itself it's too small because I only have a TextView and an EditText so what I'm doing wrong?
This is my xml.
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center" >
    <FrameLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="15dp" >
        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:background="#fff"
            android:orientation="vertical"
            android:padding="10dp" >
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Choose the receiver"
                android:textColor="@color/blue"
                android:textSize="16dp" />
            <EditText
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="15dp"
                android:background="@drawable/edittext_style"
                android:hint="Username"
                android:padding="5dp"
                android:singleLine="true"
                android:textColorHint="@color/wallet_holo_blue_light" />
        </LinearLayout>
    </FrameLayout>
    <ImageView
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_gravity="center_horizontal|top"
        android:src="@drawable/icon_mail" />
</FrameLayout>
</FrameLayout>
OUTPUT
Also I've a Drawable to put it on the Dialog to create a border roundered with color and if I put it on LinearLayout it doesn't show up.
This is the rounded_border.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
    <shape android:shape="rectangle" >
        <solid android:color="@color/white" />
        <corners android:radius="12dip" />
        <stroke
            android:width="1dip"
            android:color="@color/wallet_holo_blue_light" />
    </shape>
</item>
If I change the size of the ImageView happens this : 


 
     
     
    