Mayavi on Linux; closing a window won't let another operations in the notebook.

[jmp75]

mayavi (4.6.2)            - 3D scientific data visualization library and application
  INSTALLED: 4.6.2 (latest)

$ conda list | grep qt
pyqt                      5.9.2            py36h05f1152_2  
pyqt5                     5.12                     pypi_0    pypi
pyqt5-sip                 4.19.14                  pypi_0    pypi
qt                        5.9.7                h5867ecd_1  
qtconsole                 4.4.3                    py36_0  

[jmp75]

tried with optirun, which solves this issue, but the notebook still hangs. I have to press a "wait" button while mayavi does its work; it may be what ends up blocking the notebook from further executions.