In a page with graphic context like a vtk scene, sometimes the graphical buffer is overloaded with the use of other pages with more graphical context. This creates a race for resources in the system, which deletes the unused ones. Typically, everything is stored in the cached variables, so the issue is to reload the graphical context on page activation. However, this is a lengthy process that shall be avoided if the context is preserved.
I could add an event on page reload to launch the redraw of the scene. But I need a way to check if the scene has really lost its connection to the graphical system.
EDIT: If you want to replicate, just create two scenes and load them at the same time. Try to load some big ones, so each uses most of your card. you will see “lost graphical context” in one of them.