<bugfix>Fix issue when setting a vistrail variable on multiple modules</bugfix> <ticket>#571</ticket>
<bugfix>Fix issue when setting a vistrail variable on multiple modules</bugfix>
<ticket>#571</ticket>

The _var_selected_port variable was not being properly reset on dragLeaveEvent and dropEvent.

gui/pipeline_view.py:
  - QPipelineView.dragLeaveEvent: new method
  - QPipelineView.dropEvent: set _var_selected_port to None at the end

Nikea/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,celiafish/VisTrails,celiafish/VisTrails,Nikea/VisTrails,minesense/VisTrails,minesense/VisTrails,Nikea/VisTrails,hjanime/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,minesense/VisTrails