title: Android MapView control change background color without affecting other visual properties
body: <p>I have an Android application that uses a <code>MapView</code> with an <code>ImageButton</code> control (to move to the user's current location) I've added in the top right-hand corner.  The problem I am having is that the ImageButton control's background is too transparent, but changing it with <code>android:background="#BBFFFFFF"</code> alters both the size of the background and removes the blue "flash" that you normally see when the button is pressed - two qualities I wish to retain.</p>
  
  <p>I start with something like this:</p>
  
  <pre><code>&lt;RelativeLayout 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" &gt;
  
  &lt;com.google.android.maps.MapView
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/mapview"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:clickable="true"
  android:apiKey="my api key"
  /&gt;
  
  &lt;ImageButton android:id="@+id/googlemaps_select_location"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentTop="true"
      android:layout_alignParentRight="true"
      android:layout_marginTop="13dp"
      android:layout_marginRight="13dp"
  
      android:src="@drawable/device_access_location_found"/&gt; 
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>Which achieves something that looks like this:</p>
  
  <p><img src="https://i.imgur.com/Puo66.png" alt="ImageButton control with background that is too transparent"></p>
  
  <p>So then I add:</p>
  
  <pre><code>android:background="#BBFFFFFF"
  </code></pre>
  
  <p>And I get this:</p>
  
  <p><img src="https://i.stack.imgur.com/0eEmZ.png" alt="ImageButton control with more opaque background but other properties affected"></p>
  
  <p>Note that although this is basically the level of opacity I want, changing the background has affected the padding, and also doesn't display a blue "flash" when pressed (which obviously isn't illustrated in this question).</p>
  
  <p>So my question is, how can I change just the background color/opacity in the non-pressed state, while retaining the other visual qualities of the button?  I had a brief read about Android styles and themes, but can't even figure out where this button is getting its style/theme from and how I would go about just overriding the background color/opacity while retaining all of the other visual features. </p>