2/3 Times I encountered this window message during assign solid section. Unfortunately I can’t expand the window
This is an error message from the visualization library - Activiz VTK. Unfortunately, the source code is closed, and I cannot (I don’t know how) determine what is wrong.
For me, this window opens on other occasions, but I can continue working on the model. I recommend serving the model and restarting the PrePoMax.
For me it’s rather rare issue. I’ve seen it only a few times and was always able to continue working with this window in the background (I didn’t close it to avoid being forced to quit PrePoMax). Then I saved the model and restarted as Matej said.