Vates Simple Interface and virtual desktops on RHEL 6 can crash MantidPlot

[mantid-builder]

Original Reporter: @DennisMikkelson

The following steps consistently crash MantidPlot on RHEL 6 and Scientific Linux.

1. Load a TOPAZ file, for example TOPAZ_6251_event.nxs
2. ConvertToMD
3. Bring up the Vates Simple Interface (VSI) for the MD workspace
4. Choose the scatter plot icon
5. Switch to a different virtual desktop
6. Switch back to the virtual desktop with MantidPlot and the VSI
7. At this point the VSI window is still present, but the scatter plot is empty.
8. Choose the scatter plot icon again, and MantidPlot will seg fault.

The parameters used when loading and converting to MD are recorded in the script below:

Load(Filename='TOPAZ_6251_event.nxs',OutputWorkspace='TOPAZ_6251_event')

ConvertToMD(InputWorkspace='TOPAZ_6251_event',OutputWorkspace='TOPAZ_6251_MD',QDimensions='Q3D',
dEAnalysisMode='Elastic',LorentzCorrection='1',MinValues='25,-25,-25',MaxValues='25,25,25',
SplitInto='2,2,2',SplitThreshold='50',MaxRecursionDepth='13',MinRecursionDepth='7')

[mantid-builder]

This issue was originally trac ticket 6353