Fixes #1632

Author: dcwhite

src/Interface/Application/ModuleWidget.cc

@@ -829,6 +829,7 @@ void PortWidgetManager::addPort(OutputPortWidget* port)
 void PortWidgetManager::addPort(InputPortWidget* port)
 {
   inputPorts_.push_back(port);
+  port->setSceneFunc(getScene_);
 }
 
 void PortWidgetManager::insertPort(int index, InputPortWidget* port)
@@ -837,6 +838,7 @@ void PortWidgetManager::insertPort(int index, InputPortWidget* port)
     inputPorts_.push_back(port);
   else
     inputPorts_.insert(inputPorts_.begin() + index, port);
+  port->setSceneFunc(getScene_);
 }
 
 void PortWidgetManager::setHighlightPorts(bool on)

src/Interface/Application/Port.cc

@@ -606,7 +606,7 @@ void PortWidget::forEachPort(Func func, Pred pred)
 
 void PortWidget::makePotentialConnectionLine(PortWidget* other)
 {
-  if (getScene_() != other->getScene_())
+  if (other && getScene_ && other->getScene_ && getScene_() != other->getScene_())
     return;
 
   auto potentials = potentialConnectionsMap_[this];