3 files changed, 18 insertions, 8 deletions
diff --git a/src/quickcontrols2/qquickstyle.cpp b/src/quickcontrols2/qquickstyle.cpp
index fd81d1dd19..ec0b5e4880 100644
--- a/src/quickcontrols2/qquickstyle.cpp
+++ b/src/quickcontrols2/qquickstyle.cpp
@@ -142,6 +142,9 @@ struct QQuickStyleSpec
 
     void setFallbackStyle(const QString &fallback, const QByteArray &method)
     {
+        if (!fallback.isEmpty())
+            qCDebug(lcQtQuickControlsStyle) << "fallback style" << fallback << "set on QQuickStyleSpec via" << method;
+
         fallbackStyle = fallback;
         fallbackMethod = method;
     }
diff --git a/src/quickcontrols2/qquickstyleplugin.cpp b/src/quickcontrols2/qquickstyleplugin.cpp
index 657b31fc60..f211d4b0ae 100644
--- a/src/quickcontrols2/qquickstyleplugin.cpp
+++ b/src/quickcontrols2/qquickstyleplugin.cpp
@@ -41,7 +41,6 @@
 #include <QtCore/qloggingcategory.h>
 #include <QtQml/qqmlengine.h>
 #include <QtQml/qqmlfile.h>
-
 #include <QtQuickTemplates2/private/qquicktheme_p_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -57,17 +56,24 @@ QQuickStylePlugin::~QQuickStylePlugin()
 {
 }
 
-QString QQuickStylePlugin::name() const
-{
-    return QString();
-}
-
 void QQuickStylePlugin::registerTypes(const char *uri)
 {
     qCDebug(lcStylePlugin).nospace() << "registerTypes called with uri " << uri << "; plugin name is " << name();
 
-    if (!QQuickTheme::instance())
+    auto theme = QQuickTheme::instance();
+    if (!theme) {
         qWarning() << "QtQuick.Controls must be imported before importing" << baseUrl().toString();
+        return;
+    }
+
+    if (name() != QQuickStyle::name()) {
+        qCDebug(lcStylePlugin).nospace() << "theme does not belong to current style ("
+            << QQuickStyle::name() << "); not calling initializeTheme()";
+        return;
+    }
+
+    qCDebug(lcStylePlugin) << "theme has not been initialized; calling initializeTheme()";
+    initializeTheme(theme);
 }
 
 void QQuickStylePlugin::unregisterTypes()
diff --git a/src/quickcontrols2/qquickstyleplugin_p.h b/src/quickcontrols2/qquickstyleplugin_p.h
index 37d070dbe7..1a941aa797 100644
--- a/src/quickcontrols2/qquickstyleplugin_p.h
+++ b/src/quickcontrols2/qquickstyleplugin_p.h
@@ -63,7 +63,8 @@ public:
     explicit QQuickStylePlugin(QObject *parent = nullptr);
     ~QQuickStylePlugin();
 
-    virtual QString name() const;
+    virtual QString name() const = 0;
+    virtual void initializeTheme(QQuickTheme *theme) = 0;
 
     void registerTypes(const char *uri) override;
     void unregisterTypes() override;