Back button now returns to start screen. Also fix #356

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsActivity.kt

@@ -16,6 +16,15 @@ class SettingsActivity : BaseActivity(),
 
     private lateinit var replaceFragmentStrategy: ReplaceFragment
 
+    /**
+     * Flags to send to the parent activity for reacting to preference changes.
+     */
+    var parentFlags = 0
+        set(value) {
+            field = field or value
+            setResult(field)
+        }
+
     override fun onCreate(savedState: Bundle?) {
         setAppTheme()
         super.onCreate(savedState)
@@ -29,10 +38,16 @@ class SettingsActivity : BaseActivity(),
             supportFragmentManager.beginTransaction()
                 .add(R.id.settings_content, SettingsFragment.newInstance(null), "Settings")
                 .commit()
+        } else {
+            parentFlags = savedState.getInt(SettingsActivity::parentFlags.name)
         }
 
         setupToolbar(toolbar, backNavigation = false)
+    }
 
+    override fun onSaveInstanceState(outState: Bundle) {
+        outState.putInt(SettingsActivity::parentFlags.name, parentFlags)
+        super.onSaveInstanceState(outState)
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -60,4 +75,9 @@ class SettingsActivity : BaseActivity(),
         return true
     }
 
+    companion object {
+        const val FLAG_THEME_CHANGED = 0x1
+        const val FLAG_DATABASE_CLEARED = 0x2
+    }
+
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsAdvancedFragment.kt

@@ -97,6 +97,7 @@ class SettingsAdvancedFragment : SettingsFragment() {
                 .positiveText(android.R.string.yes)
                 .negativeText(android.R.string.no)
                 .onPositive { dialog, which ->
+                    (activity as SettingsActivity).parentFlags = SettingsActivity.FLAG_DATABASE_CLEARED
                     db.deleteMangasNotInLibrary().executeAsBlocking()
                     activity.toast(R.string.clear_database_completed)
                 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsGeneralFragment.kt

@@ -1,8 +1,6 @@
 package eu.kanade.tachiyomi.ui.setting
 
-import android.content.Intent
 import android.os.Bundle
-import android.support.v4.app.TaskStackBuilder
 import android.support.v7.preference.Preference
 import android.support.v7.preference.PreferenceFragmentCompat
 import android.support.v7.preference.XpPreferenceFragment
@@ -67,16 +65,14 @@ class SettingsGeneralFragment : SettingsFragment(),
         }
 
         themePreference.setOnPreferenceChangeListener { preference, newValue ->
-            // Rebuild activity's to apply themes.
-            TaskStackBuilder.create(context)
-                    .addNextIntentWithParentStack(Intent(activity.intent))
-                    .startActivities()
+            (activity as SettingsActivity).parentFlags = SettingsActivity.FLAG_THEME_CHANGED
+            activity.recreate()
             true
         }
     }
 
     override fun onPreferenceDisplayDialog(p0: PreferenceFragmentCompat?, p: Preference): Boolean {
-        if (p.key == getString(R.string.pref_library_columns_dialog_key)) {
+        if (p === columnsPreference) {
             val fragment = LibraryColumnsDialog.newInstance(p)
             fragment.setTargetFragment(this, 0)
             fragment.show(fragmentManager, null)