Add GraphicsWindow ref check
Add GraphicsWindow ref check

derricw/pyqtgraph,ericdill/pyqtgraph,ddamiani/pyqtgraph,acq4/acq4,campagnola/acq4,gvalentine/pyqtgraph,pbmanis/acq4,meganbkratz/acq4,pbmanis/acq4,gvalentine/pyqtgraph,vallsv/pyqtgraph,mpvismer/pyqtgraph,ng110/pyqtgraph,Lx37/pyqtgraph,tropp/acq4,meganbkratz/acq4,onlyjus/pyqtgraph,nmearl/pyqtgraph,JenSte/pyqtgraph,onlyjus/pyqtgraph,tropp/acq4,tropp/acq4,meganbkratz/acq4,duguxy/pyqtgraph,Lx37/pyqtgraph,duguxy/pyqtgraph,benvermaercke/pyqtgraph,pmaunz/pyqtgraph,petebachant/pyqtgraph,jlombacher/pyqtgraph,campagnola/acq4,mgraupe/acq4,mpvismer/pyqtgraph,gvalentine/pyqtgraph,benvermaercke/pyqtgraph,acq4/acq4,mgraupe/acq4,tropp/acq4,vallsv/pyqtgraph,stscieisenhamer/pyqtgraph,mgraupe/acq4,jlombacher/pyqtgraph,campagnola/acq4,ddamiani/pyqtgraph,welshjf/pyqtgraph,pbmanis/acq4,onlyjus/pyqtgraph,carlomt/dicom_tools,ddamiani/pyqtgraph,pbmanis/acq4,welshjf/pyqtgraph,ericdill/pyqtgraph,pmaunz/pyqtgraph,benvermaercke/pyqtgraph,campagnola/acq4,ng110/pyqtgraph,carlomt/dicom_tools,petebachant/pyqtgraph,derricw/pyqtgraph,welshjf/pyqtgraph,JenSte/pyqtgraph,meganbkratz/acq4,mgraupe/acq4,ericdill/pyqtgraph,acq4/acq4,mgraupe/acq4,stscieisenhamer/pyqtgraph,acq4/acq4,nmearl/pyqtgraph