prefs dependency

res/xml/pref_bluetooth.xml

@@ -13,11 +13,13 @@
 
 	<de.duenndns.BluetoothDevicePreference
 		android:key="bt.mac"
+		android:dependency="bt.client"
 		android:title="TNC Bluetooth Device"
 		android:summary="You need to pair it from the system preferences"
 		android:dialogTitle="choose device" />
         <EditTextPreference
                 android:key="bt.channel"
+		android:dependency="bt.client"
 		android:inputType="number"
 		android:title="Channel"
 		android:summary="Usually this is '1'"