KCM KWinTabbox activate/deactivate desktop effects. Fix default value for highlightWindowsEnabled

src/kcmkwin/kwintabbox/kwinpluginssettings.kcfg

@@ -12,7 +12,7 @@
             <default code="true">BuiltInEffects::enabledByDefault(BuiltInEffect::FlipSwitch)</default>
         </entry>
         <entry key="highlightwindowEnabled" type="Bool">
-            <default>false</default>
+            <default code="true">BuiltInEffects::enabledByDefault(BuiltInEffect::HighlightWindow)</default>
         </entry>
     </group>
 </kcfg>

src/kcmkwin/kwintabbox/main.cpp

@@ -344,16 +344,10 @@ void KWinTabBoxConfig::save()
     const bool flipSwitchAlternative = m_alternativeTabBoxUi->showTabBox()
             && m_alternativeTabBoxUi->effectComboCurrentData().toString() == m_flipSwitch;
 
-    // activate effects if not active
-    if (coverSwitch || coverSwitchAlternative) {
-        m_data->pluginsConfig()->setCoverswitchEnabled(true);
-    }
-    if (flipSwitch || flipSwitchAlternative) {
-        m_data->pluginsConfig()->setFlipswitchEnabled(true);
-    }
-    if (highlightWindows) {
-        m_data->pluginsConfig()->setHighlightwindowEnabled(true);
-    }
+    // activate effects if they are used otherwise deactivate them.
+    m_data->pluginsConfig()->setCoverswitchEnabled(coverSwitch || coverSwitchAlternative);
+    m_data->pluginsConfig()->setFlipswitchEnabled(flipSwitch || flipSwitchAlternative);
+    m_data->pluginsConfig()->setHighlightwindowEnabled(highlightWindows);
     m_data->pluginsConfig()->save();
 
     m_data->coverSwitchConfig()->setTabBox(coverSwitch);