Thanks at all for all your help for now.I have another little issues

This is a portion of my layout which give me some problems:

<RelativeLayout android:id="@+id/card_address_layout"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="visible"
            >
                 <TextView
                    style="@style/card_field"
                    android:id="@+id/card_indirizzo"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    android:layout_gravity="left|center_vertical"                     
                    android:layout_marginTop="8dp"                 
                    android:maxLength="35"
                    android:ellipsize="marquee"

                 /> 

                 <ImageButton 
                    android:id="@+id/card_address_button"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="right|center_vertical"
                    android:layout_toRightOf="@id/card_indirizzo"
                    android:src="@drawable/map_selector"
                    android:onClick="startMap"
                    android:padding="0dp"  />

         </RelativeLayout>

The image button src is a selector, in this case this one:

 <selector xmlns:android="http://schemas.android.com/apk/res/android">
 <item android:state_pressed="true" android:drawable="@drawable/map_b" /> <!-- pressed -->
 <item android:drawable="@drawable/map_a" />                 <!-- default -->

This is the result and I really don't understand why, why the image button has padding??!!!

Help meeeee!