fix font preview in labeling

Author: jef-n

src/app/qgslabelpreview.h

@@ -12,12 +12,16 @@ class QgsLabelPreview : public QLabel
 
     void setBuffer( double size, QColor color );
 
+    void setFont( QFont f ) { mFont = f; }
+    QFont font() { return mFont; }
+
     void paintEvent( QPaintEvent* e );
 
   private:
     int mBufferSize;
     QColor mBufferColor;
     QColor mTextColor;
+    QFont mFont;
 };
 
 #endif // LABELPREVIEW_H