[libcalamaresui] Less mutex shenanigans

src/libcalamaresui/viewpages/Slideshow.cpp

@@ -117,11 +117,8 @@ SlideshowQML::loadQmlV2Complete()
             {
                 // We're alreay visible! Must have been slow QML loading, and we
                 // passed onActivate already. changeSlideShowState() locks
-                // the same mutex: we could set up a workaround to call
-                // changeSlideShowState() later after destruction of l.
-                //
-                l.unlock();
-                changeSlideShowState( Slideshow::Start );
+                // the same mutex: call changeSlideShowState() after l is dead.
+                QTimer::singleShot( 0, this, &SlideshowQML::startSlideShow );
             }
         }
     }
@@ -142,6 +139,13 @@ SlideshowQML::loadQmlV2Complete()
     }
 }
 
+void
+SlideshowQML::startSlideShow()
+{
+    changeSlideShowState( Slideshow::Start );
+}
+
+
 /*
  * Applies V1 and V2 QML activation / deactivation:
  *  - V1 loads the QML in @p widget on activation. Sets root object property

src/libcalamaresui/viewpages/Slideshow.h

@@ -100,6 +100,9 @@ public slots:
     void loadQmlV2Complete();
     void loadQmlV2();  ///< Loads the slideshow QML (from branding) for API version 2
 
+    /// Implementation detail
+    void startSlideShow();
+
 private:
     QQuickWidget* m_qmlShow;
     QQmlComponent* m_qmlComponent;