diff --git a/kcmkwin/kwincompositing/model.cpp b/kcmkwin/kwincompositing/model.cpp
index 1426c472c1..3b2f158e19 100644
--- a/kcmkwin/kwincompositing/model.cpp
+++ b/kcmkwin/kwincompositing/model.cpp
@@ -80,6 +80,11 @@ static QString translatedCategory(const QString &category)
     return translatedCategories[index];
 }
 
+static EffectStatus effectStatus(bool enabled)
+{
+    return enabled ? EffectStatus::Enabled : EffectStatus::Disabled;
+}
+
 EffectModel::EffectModel(QObject *parent)
     : QAbstractItemModel(parent) {
 }
@@ -160,7 +165,7 @@ QVariant EffectModel::data(const QModelIndex &index, int role) const
         case ServiceNameRole:
             return m_effectsList.at(index.row()).serviceName;
         case EffectStatusRole:
-            return m_effectsList.at(index.row()).effectStatus;
+            return (int)m_effectsList.at(index.row()).effectStatus;
         case VideoRole:
             return m_effectsList.at(index.row()).video;
         case SupportedRole:
@@ -188,11 +193,11 @@ bool EffectModel::setData(const QModelIndex& index, const QVariant& value, int r
         // gets marked as changed and will get saved to the config file. This means the
         // config file could get polluted
         EffectData &data = m_effectsList[index.row()];
-        data.effectStatus = value.toBool();
+        data.effectStatus = EffectStatus(value.toInt());
         data.changed = true;
         emit dataChanged(index, index);
 
-        if (data.effectStatus && !data.exclusiveGroup.isEmpty()) {
+        if (data.effectStatus == EffectStatus::Enabled && !data.exclusiveGroup.isEmpty()) {
             // need to disable all other exclusive effects in the same category
             for (int i = 0; i < m_effectsList.size(); ++i) {
                 if (i == index.row()) {
@@ -200,7 +205,7 @@ bool EffectModel::setData(const QModelIndex& index, const QVariant& value, int r
                 }
                 EffectData &otherData = m_effectsList[i];
                 if (otherData.exclusiveGroup == data.exclusiveGroup) {
-                    otherData.effectStatus = false;
+                    otherData.effectStatus = EffectStatus::Disabled;
                     otherData.changed = true;
                     emit dataChanged(this->index(i, 0), this->index(i, 0));
                 }
@@ -234,7 +239,15 @@ void EffectModel::loadEffects()
         effect.category = translatedCategory(data.category);
         effect.serviceName = data.name;
         effect.enabledByDefault = data.enabled;
-        effect.effectStatus = kwinConfig.readEntry(effect.serviceName + "Enabled", effect.enabledByDefault);
+        effect.enabledByDefaultFunction = (data.enabledFunction != nullptr);
+        const QString enabledKey = QStringLiteral("%1Enabled").arg(effect.serviceName);
+        if (kwinConfig.hasKey(enabledKey)) {
+            effect.effectStatus = effectStatus(kwinConfig.readEntry(effect.serviceName + "Enabled", effect.enabledByDefault));
+        } else if (data.enabledFunction != nullptr) {
+            effect.effectStatus = EffectStatus::EnabledUndeterminded;
+        } else {
+            effect.effectStatus = effectStatus(effect.enabledByDefault);
+        }
         effect.video = data.video;
         effect.supported = true;
         effect.exclusiveGroup = data.exclusiveCategory;
@@ -262,8 +275,9 @@ void EffectModel::loadEffects()
         effect.version = plugin.version();
         effect.category = translatedCategory(plugin.category());
         effect.serviceName = plugin.pluginName();
-        effect.effectStatus = kwinConfig.readEntry(effect.serviceName + "Enabled", plugin.isPluginEnabledByDefault());
+        effect.effectStatus = effectStatus(kwinConfig.readEntry(effect.serviceName + "Enabled", plugin.isPluginEnabledByDefault()));
         effect.enabledByDefault = plugin.isPluginEnabledByDefault();
+        effect.enabledByDefaultFunction = false;
         effect.video = service->property(QStringLiteral("X-KWin-Video-Url"), QVariant::Url).toUrl();
         effect.supported = true;
         effect.exclusiveGroup = service->property(QStringLiteral("X-KWin-Exclusive-Category"), QVariant::String).toString();
@@ -350,7 +364,7 @@ void EffectModel::syncEffectsToKWin()
                                              QDBusConnection::sessionBus());
     for (int it = 0; it < m_effectsList.size(); it++) {
         if (m_effectsList.at(it).effectStatus != m_effectsChanged.at(it).effectStatus) {
-            if (m_effectsList.at(it).effectStatus) {
+            if (m_effectsList.at(it).effectStatus != EffectStatus::Disabled) {
                 interface.loadEffect(m_effectsList.at(it).serviceName);
             } else {
                 interface.unloadEffect(m_effectsList.at(it).serviceName);
@@ -361,9 +375,9 @@ void EffectModel::syncEffectsToKWin()
     m_effectsChanged = m_effectsList;
 }
 
-void EffectModel::updateEffectStatus(const QModelIndex &rowIndex, bool effectState)
+void EffectModel::updateEffectStatus(const QModelIndex &rowIndex, EffectStatus effectState)
 {
-    setData(rowIndex, effectState, EffectModel::EffectStatusRole);
+    setData(rowIndex, (int)effectState, EffectModel::EffectStatusRole);
 }
 
 void EffectModel::syncConfig()
@@ -378,11 +392,14 @@ void EffectModel::syncConfig()
         effect.changed = false;
 
         const QString key = effect.serviceName + QStringLiteral("Enabled");
-
-        if (effect.effectStatus != effect.enabledByDefault) {
-            kwinConfig.writeEntry(key, effect.effectStatus);
-        } else {
+        const bool shouldEnable = (effect.effectStatus != EffectStatus::Disabled);
+        const bool restoreToDefault = effect.enabledByDefaultFunction
+                                      ? effect.effectStatus == EffectStatus::EnabledUndeterminded
+                                      : shouldEnable == effect.enabledByDefault;
+        if (restoreToDefault) {
             kwinConfig.deleteEntry(key);
+        } else {
+            kwinConfig.writeEntry(key, shouldEnable);
         }
     }
 
@@ -394,8 +411,10 @@ void EffectModel::defaults()
 {
     for (int i = 0; i < m_effectsList.count(); ++i) {
         const auto &effect = m_effectsList.at(i);
-        if (effect.effectStatus != effect.enabledByDefault) {
-            updateEffectStatus(index(i, 0), effect.enabledByDefault);
+        if (effect.enabledByDefaultFunction && effect.effectStatus != EffectStatus::EnabledUndeterminded) {
+            updateEffectStatus(index(i, 0), EffectStatus::EnabledUndeterminded);
+        } else if ((bool)effect.effectStatus != effect.enabledByDefault) {
+            updateEffectStatus(index(i, 0), effect.enabledByDefault ? EffectStatus::Enabled : EffectStatus::Disabled);
         }
     }
 }
@@ -472,11 +491,11 @@ bool EffectFilterModel::filterAcceptsRow(int source_row, const QModelIndex &sour
     return false;
 }
 
-void EffectFilterModel::updateEffectStatus(int rowIndex, bool effectState)
+void EffectFilterModel::updateEffectStatus(int rowIndex, int effectState)
 {
     const QModelIndex sourceIndex = mapToSource(index(rowIndex, 0));
 
-    m_effectModel->updateEffectStatus(sourceIndex, effectState);
+    m_effectModel->updateEffectStatus(sourceIndex, EffectStatus(effectState));
 }
 
 void EffectFilterModel::syncConfig()
diff --git a/kcmkwin/kwincompositing/model.h b/kcmkwin/kwincompositing/model.h
index fc7f7dad25..b863b1b371 100644
--- a/kcmkwin/kwincompositing/model.h
+++ b/kcmkwin/kwincompositing/model.h
@@ -34,6 +34,12 @@
 namespace KWin {
 namespace Compositing {
 
+enum class EffectStatus {
+    Disabled = Qt::Unchecked,
+    EnabledUndeterminded = Qt::PartiallyChecked,
+    Enabled = Qt::Checked
+};
+
 struct EffectData {
     QString name;
     QString description;
@@ -43,8 +49,9 @@ struct EffectData {
     QString version;
     QString category;
     QString serviceName;
-    bool effectStatus;
+    EffectStatus effectStatus;
     bool enabledByDefault;
+    bool enabledByDefaultFunction;
     QUrl video;
     bool supported;
     QString exclusiveGroup;
@@ -90,7 +97,7 @@ public:
 
     virtual QHash< int, QByteArray > roleNames() const override;
 
-    void updateEffectStatus(const QModelIndex &rowIndex, bool effectState);
+    void updateEffectStatus(const QModelIndex &rowIndex, EffectStatus effectState);
     void syncEffectsToKWin();
     void syncConfig();
     void loadEffects();
@@ -153,7 +160,7 @@ public:
     EffectFilterModel(QObject *parent = 0);
     const QString &filter() const;
 
-    Q_INVOKABLE void updateEffectStatus(int rowIndex, bool effectState);
+    Q_INVOKABLE void updateEffectStatus(int rowIndex, int effectState);
     Q_INVOKABLE void syncConfig();
     Q_INVOKABLE void load();
 
diff --git a/kcmkwin/kwincompositing/qml/Effect.qml b/kcmkwin/kwincompositing/qml/Effect.qml
index e05ab81cef..0c46ef3b44 100644
--- a/kcmkwin/kwincompositing/qml/Effect.qml
+++ b/kcmkwin/kwincompositing/qml/Effect.qml
@@ -30,7 +30,7 @@ Rectangle {
     height: rowEffect.implicitHeight
     color: item.ListView.isCurrentItem ? effectView.backgroundActiveColor : index % 2 ? effectView.backgroundNormalColor : effectView.backgroundAlternateColor
     signal changed()
-    property bool checked: model.EffectStatusRole
+    property int checkedState: model.EffectStatusRole
 
     MouseArea {
         anchors.fill: parent
@@ -61,7 +61,7 @@ Rectangle {
                         return;
                     }
                     actuallyChanged = true;
-                    item.checked = exclusiveGroupButton.checked
+                    item.checkedState = exclusiveGroupButton.checked ? Qt.Checked : Qt.UnChecked
                     item.changed();
                 }
                 onClicked: {
@@ -78,20 +78,20 @@ Rectangle {
 
             CheckBox {
                 id: effectStatusCheckBox
-                checked: model.EffectStatusRole
+                checkedState: model.EffectStatusRole
                 visible: model.ExclusiveRole == ""
 
-                onCheckedChanged: {
+                onCheckedStateChanged: {
                     if (!visible) {
                         return;
                     }
-                    item.checked = effectStatusCheckBox.checked;
+                    item.checkedState = effectStatusCheckBox.checkedState;
                     item.changed();
                 }
                 Connections {
                     target: searchModel
                     onDataChanged: {
-                        effectStatusCheckBox.checked = model.EffectStatusRole;
+                        effectStatusCheckBox.checkedState = model.EffectStatusRole;
                     }
                 }
             }
@@ -140,7 +140,7 @@ Rectangle {
         Button {
             id: configureButton
             visible: ConfigurableRole
-            enabled: effectStatusCheckBox.checked
+            enabled: item.checkedState != Qt.UnChecked
             iconName: "configure"
             onClicked: {
                 effectConfig.openConfig(model.ServiceNameRole, model.ScriptedRole, model.NameRole);
diff --git a/kcmkwin/kwincompositing/qml/EffectView.qml b/kcmkwin/kwincompositing/qml/EffectView.qml
index 4db0818273..4118b3f96e 100644
--- a/kcmkwin/kwincompositing/qml/EffectView.qml
+++ b/kcmkwin/kwincompositing/qml/EffectView.qml
@@ -111,11 +111,6 @@ Item {
             id: searchModel
             objectName: "filterModel"
             filter: searchField.text
-            signal effectState(int rowIndex, bool enabled)
-
-            onEffectState: {
-                searchModel.updateEffectStatus(rowIndex, enabled);
-            }
         }
 
         ScrollView {
@@ -157,7 +152,9 @@ Item {
                     Connections {
                         id: effectStateConnection
                         target: null
-                        onChanged: searchModel.effectState(index, checked)
+                        onChanged: {
+                            searchModel.updateEffectStatus(index, checkedState);
+                        }
                     }
                     Component.onCompleted: {
                         effectStateConnection.target = effectDelegate
@@ -174,6 +171,6 @@ Item {
     }//End ColumnLayout
     Connections {
         target: searchModel
-        onEffectState: changed()
+        onDataChanged: changed()
     }
 }//End item