hide screen security when unsupported

// FREEBIE

res/xml/preferences.xml

@@ -156,7 +156,7 @@
 
     </PreferenceCategory>
 
-    <PreferenceCategory android:title="@string/preferences__advanced">
+    <PreferenceCategory android:key="advanced_category" android:title="@string/preferences__advanced">
        <CheckBoxPreference android:defaultValue="true"
                            android:key="pref_auto_complete_key_exchange"
                            android:title="@string/preferences__complete_key_exchanges"

src/org/thoughtcrime/securesms/ApplicationPreferencesActivity.java

@@ -193,10 +193,12 @@ public class ApplicationPreferencesActivity extends PassphraseRequiredSherlockPr
   }
 
   private void initializePlatformSpecificOptions() {
-    PreferenceGroup    pushSmsCategory    = (PreferenceGroup) findPreference("push_sms_category");
+    PreferenceGroup    pushSmsCategory          = (PreferenceGroup) findPreference("push_sms_category");
-    Preference         defaultPreference  = findPreference(KITKAT_DEFAULT_PREF);
+    PreferenceGroup    advancedCategory         = (PreferenceGroup) findPreference("advanced_category");
-    Preference         allSmsPreference   = findPreference(TextSecurePreferences.ALL_SMS_PREF);
+    Preference         defaultPreference        = findPreference(KITKAT_DEFAULT_PREF);
-    Preference         allMmsPreference   = findPreference(TextSecurePreferences.ALL_MMS_PREF);
+    Preference         allSmsPreference         = findPreference(TextSecurePreferences.ALL_SMS_PREF);
+    Preference         allMmsPreference         = findPreference(TextSecurePreferences.ALL_MMS_PREF);
+    Preference         screenSecurityPreference = findPreference(TextSecurePreferences.SCREEN_SECURITY_PREF);
 
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && pushSmsCategory != null) {
       if (allSmsPreference != null) pushSmsCategory.removePreference(allSmsPreference);
@@ -216,6 +218,13 @@ public class ApplicationPreferencesActivity extends PassphraseRequiredSherlockPr
     } else if (pushSmsCategory != null && defaultPreference != null) {
       pushSmsCategory.removePreference(defaultPreference);
     }
+
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1 &&
+        advancedCategory != null                                   &&
+        screenSecurityPreference != null)
+    {
+      advancedCategory.removePreference(screenSecurityPreference);
+    }
   }
 
   private void initializeEditTextSummary(final EditTextPreference preference) {

src/org/thoughtcrime/securesms/util/TextSecurePreferences.java

@@ -29,7 +29,7 @@ public class TextSecurePreferences {
   private static final String PASSPHRASE_TIMEOUT_INTERVAL_PREF = "pref_timeout_interval";
   private static final String PASSPHRASE_TIMEOUT_PREF          = "pref_timeout_passphrase";
   private static final String AUTO_KEY_EXCHANGE_PREF           = "pref_auto_complete_key_exchange";
-  private static final String SCREEN_SECURITY_PREF             = "pref_screen_security";
+  public  static final String SCREEN_SECURITY_PREF             = "pref_screen_security";
   private static final String ENTER_SENDS_PREF                 = "pref_enter_sends";
   private static final String ENTER_PRESENT_PREF               = "pref_enter_key";
   private static final String SMS_DELIVERY_REPORT_PREF         = "pref_delivery_report_sms";