Fix resize cursor not being cleared when mouse moves over child widgets

plugins/samplesource/hackrfinput/hackrfinputgui.cpp

@@ -73,6 +73,7 @@ HackRFInputGui::HackRFInputGui(DeviceUISet *deviceUISet, QWidget* parent) :
 
     sendSettings();
     makeUIConnections();
+    m_resizer.enableChildMouseTracking();
 }
 
 HackRFInputGui::~HackRFInputGui()