Workbench state not persisting in Mayavi

Reports from the Mayavi team that state of perspectives is not being stored properly:

> If you run mayavi2, for the first time, the default perspective is OK but if you close it and restart, or change it, or even create a new perspective, you get a terribly messed up perspective with the editor area being very tiny. Am happy to share a screenshot but this is almost trivial to reproduce. Just run mayavi2 with a qt backend twice on the terminal.