KCM KWinCompositing implement KCModuleData to highlight default at module level

Fix Rendering backend combobox that was not highlighted.
Particular case due to OpenGLIsUnsafe kcfg entry which is an indicating
flag and not a configurable setting.

kcmkwin/kwincompositing/CMakeLists.txt

@@ -10,6 +10,7 @@ remove_definitions(-DQT_NO_CAST_FROM_ASCII -DQT_STRICT_ITERATORS -DQT_NO_CAST_FR
 
 set(kwincompositing_SRC
     main.cpp
+    kwincompositingdata.cpp
 )
 
 kconfig_add_kcfg_files(kwincompositing_SRC kwincompositing_setting.kcfgc GENERATE_MOC)

kcmkwin/kwincompositing/kwincompositing.desktop

@@ -5,7 +5,6 @@ X-KDE-ServiceTypes=KCModule
 X-DocPath=https://userbase.kde.org/Desktop_Effects_Performance#Advanced_Desktop_Effects_Settings
 
 X-KDE-Library=kwincompositing
-X-KDE-PluginKeyword=compositing
 X-KDE-ParentApp=kcontrol
 
 X-KDE-System-Settings-Parent-Category=display

kcmkwin/kwincompositing/kwincompositingdata.cpp

@@ -0,0 +1,32 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2020 Cyril Rossi <cyril.rossi@enioka.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#include "kwincompositingdata.h"
+
+#include "kwincompositing_setting.h"
+
+KWinCompositingData::KWinCompositingData(QObject *parent, const QVariantList &args)
+    : KCModuleData(parent, args)
+    , m_settings(new KWinCompositingSetting(this))
+
+{
+}
+
+bool KWinCompositingData::isDefaults() const
+{
+    bool defaults = true;
+    for (const auto &item : m_settings->items()) {
+        if (item->key() != QStringLiteral("OpenGLIsUnsafe")) {
+            defaults &= item->isDefault();
+        }
+    }
+    return defaults;
+}
+
+#include "kwincompositingdata.moc"

kcmkwin/kwincompositing/kwincompositingdata.h

@@ -0,0 +1,32 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2020 Cyril Rossi <cyril.rossi@enioka.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#ifndef KWINCOMPOSITINGDATA_H
+#define KWINCOMPOSITINGDATA_H
+
+#include <QObject>
+
+#include "kcmoduledata.h"
+
+class KWinCompositingSetting;
+
+class KWinCompositingData : public KCModuleData
+{
+    Q_OBJECT
+
+public:
+    explicit KWinCompositingData(QObject *parent = nullptr, const QVariantList &args = QVariantList());
+
+    bool isDefaults() const override;
+
+private:
+    KWinCompositingSetting *m_settings;
+};
+
+#endif // KWINCOMPOSITINGDATA_H

kcmkwin/kwincompositing/main.cpp

@@ -23,6 +23,7 @@
 #include <functional>
 
 #include "kwincompositing_setting.h"
+#include "kwincompositingdata.h"
 
 static bool isRunningPlasma()
 {
@@ -88,6 +89,8 @@ KWinCompositingKCM::KWinCompositingKCM(QWidget *parent, const QVariantList &args
     m_form.kcfg_Enabled->setVisible(!compositingRequired());
     m_form.kcfg_WindowsBlockCompositing->setVisible(!compositingRequired());
 
+    connect(this, &KWinCompositingKCM::defaultsIndicatorsVisibleChanged, this, &KWinCompositingKCM::updateUnmanagedItemStatus);
+
     init();
 }
 
@@ -211,6 +214,10 @@ void KWinCompositingKCM::updateUnmanagedItemStatus()
     if (!inPlasma) {
         defaulted &= animationDuration == m_settings->defaultAnimationDurationFactorValue();
     }
+
+    m_form.backend->setProperty("_kde_highlight_neutral", defaultsIndicatorsVisible() && (backend != m_settings->defaultBackendValue() || glCore != m_settings->defaultGlCoreValue()));
+    m_form.backend->update();
+
     unmanagedWidgetDefaultState(defaulted);
 }
 
@@ -288,7 +295,8 @@ void KWinCompositingKCM::save()
 }
 
 K_PLUGIN_FACTORY(KWinCompositingConfigFactory,
-                 registerPlugin<KWinCompositingKCM>("compositing");
+                 registerPlugin<KWinCompositingKCM>();
+                 registerPlugin<KWinCompositingData>();
                 )
 
 #include "main.moc"