diff --git a/effects/thumbnailaside/thumbnailaside_config.cpp b/effects/thumbnailaside/thumbnailaside_config.cpp
--- a/effects/thumbnailaside/thumbnailaside_config.cpp
+++ b/effects/thumbnailaside/thumbnailaside_config.cpp
@@ -89,6 +89,7 @@
 void ThumbnailAsideEffectConfig::save()
 {
     KCModule::save();
+    m_ui->editor->save();
     OrgKdeKwinEffectsInterface interface(QStringLiteral("org.kde.KWin"),
                                          QStringLiteral("/Effects"),
                                          QDBusConnection::sessionBus());