[kcms/style] Fix setting to default and apply button enablement

Track the selected GTK theme in the model only. This fixes setting to default when the GTK pages was never opened

Override isSaveNeeded instead of calling setNeedsSave, this fixes the apply button enablement

kcms/style/gtkpage.cpp

@@ -31,12 +31,6 @@ GtkPage::GtkPage(QObject *parent)
 
 GtkPage::~GtkPage() = default;
 
-QString GtkPage::gtkThemeFromConfig()
-{
-    // FIXME make aysnc but that requires some refactoring on the UI side
-    return m_gtkConfigInterface.gtkTheme().value();
-}
-
 bool GtkPage::gtkPreviewAvailable()
 {
     return !QStandardPaths::findExecutable(QStringLiteral("gtk3_preview"), {CMAKE_INSTALL_FULL_LIBEXECDIR}).isEmpty();
@@ -94,17 +88,21 @@ void GtkPage::save()
 
 void GtkPage::defaults()
 {
-    Q_EMIT selectGtkThemeInCombobox(QStringLiteral("Breeze"));
+    m_gtkThemesModel->setSelectedTheme(QStringLiteral("Breeze"));
 }
 
 void GtkPage::load()
 {
     m_gtkThemesModel->load();
     m_gtkThemesModel->setSelectedTheme(m_gtkConfigInterface.gtkTheme());
-    Q_EMIT selectGtkThemeInCombobox(gtkThemeFromConfig());
 }
 
 bool GtkPage::isDefaults() const
 {
     return m_gtkThemesModel->selectedTheme() == QLatin1String("Breeze");
 }
+
+bool GtkPage::isSaveNeeded()
+{
+    return m_gtkThemesModel->selectedTheme() != m_gtkConfigInterface.gtkTheme();
+}

kcms/style/gtkpage.h

@@ -27,10 +27,9 @@ public:
     void save();
     void defaults();
     bool isDefaults() const;
+    bool isSaveNeeded();
 
 public Q_SLOTS:
-    QString gtkThemeFromConfig();
-
     bool gtkPreviewAvailable();
 
     void showGtkPreview();
@@ -43,7 +42,6 @@ Q_SIGNALS:
     void gtkThemesModelChanged(GtkThemesModel *model);
 
     void showErrorMessage(const QString &message);
-    void selectGtkThemeInCombobox(const QString &themeName);
 
     void gtkThemeSettingsChanged();
 

kcms/style/gtkthemesmodel.cpp

@@ -103,6 +103,7 @@ QMap<QString, QString> GtkThemesModel::themesList()
 void GtkThemesModel::setSelectedTheme(const QString &themeName)
 {
     m_selectedTheme = themeName;
+    Q_EMIT selectedThemeChanged(themeName);
 }
 
 QString GtkThemesModel::selectedTheme()

kcms/style/kcmstyle.cpp

@@ -90,7 +90,6 @@ KCMStyle::KCMStyle(QObject *parent, const KPluginMetaData &data, const QVariantL
     m_gtkPage = new GtkPage(this);
     connect(m_gtkPage, &GtkPage::gtkThemeSettingsChanged, this, [this]() {
         settingsChanged();
-        setNeedsSave(true);
     });
 }
 
@@ -338,4 +337,9 @@ bool KCMStyle::isDefaults() const
     return m_gtkPage->isDefaults();
 }
 
+bool KCMStyle::isSaveNeeded() const
+{
+    return m_gtkPage->isSaveNeeded();
+}
+
 #include "kcmstyle.moc"

kcms/style/kcmstyle.h

@@ -76,6 +76,7 @@ public:
     void defaults() override;
 
     bool isDefaults() const override;
+    bool isSaveNeeded() const override;
 
 Q_SIGNALS:
     void showErrorMessage(const QString &message);

kcms/style/package/contents/ui/GtkStylePage.qml

@@ -49,20 +49,13 @@ Kirigami.Page {
                     QtControls.ComboBox {
                         id: gtkThemeCombo
                         model: kcm.gtkPage.gtkThemesModel
-                        currentIndex: model.findThemeIndex(kcm.gtkPage.gtkThemeFromConfig())
+                        currentIndex: model.findThemeIndex(kcm.gtkPage.gtkThemesModel.selectedTheme)
                         onCurrentTextChanged: function() {
                             model.selectedTheme = currentText
                             gtkRemoveButton.enabled = model.selectedThemeRemovable()
                         }
                         onActivated: model.setSelectedThemeDirty()
                         textRole: "theme-name"
-
-                        Connections {
-                            target: kcm.gtkPage
-                            function onSelectGtkThemeInCombobox(themeName) {
-                                gtkThemeCombo.currentIndex = gtkThemeCombo.model.findThemeIndex(themeName)
-                            }
-                        }
                     }
 
                     QtControls.Button {