xrtGlow fails to load a new xml after working with a previous one

[kklmn]

Load BioXAS_Main.xml, put the virtual screen, close xrtGlow, load another xml.

QOpenGLContext::swapBuffers() called with non-exposed window, behavior is undefined
Traceback (most recent call last):
File "....\xrt\gui\xrtQook_init.py", line 3366, in blRunGlow
self.blViewer.updateOEsList(self.rayPath)
File "....\xrt\gui\xrtGlow_init.py", line 687, in updateOEsList
self.changeColorAxis(None)
File "....\xrt\gui\xrtGlow_init.py", line 983, in changeColorAxis
self.customGlWidget.populateVerticesArray(self.segmentsModelRoot)
File "....\xrt\gui\xrtGlow_init.py", line 2116, in populateVerticesArray
self.populateVScreen()
File "....\xrt\gui\xrtGlow_init_.py", line 3655, in populateVScreen
vColorArray <= self.selColorMax,
TypeError: '<=' not supported between instances of 'float' and 'NoneType'

[yxrmz]

It's because the virtual screen is still on, but the rest of the beamline doesn't exist. A temporary workaround would be to disable the virtual screen before loading the beamline XML.