Fixed build issues for issue #773

sdrbase/dsp/spectrumvis.h

@@ -107,7 +107,7 @@ public:
         {}
     };
 
-    class MsgFrequencyZooming : public Message {
+    class SDRBASE_API MsgFrequencyZooming : public Message {
         MESSAGE_CLASS_DECLARATION
 
     public:

sdrgui/gui/glspectrum.cpp

@@ -2278,7 +2278,11 @@ void GLSpectrum::wheelEvent(QWheelEvent *event)
 
 void GLSpectrum::frequencyZoom(QWheelEvent *event)
 {
+#if QT_VERSION >= QT_VERSION_CHECK(5, 14, 0)
 	const QPointF& p = event->position();
+#else
+	const QPointF& p = event->pos();
+#endif
 
 	if (event->delta() > 0) // zoom in
 	{