When updating the history, specify which of the expensive parts need to be updated.
"nlview"
"viewport"
"other"
When updating the history, specify which of the expensive parts need to be updated.
"nlview"= update the Nlview schematic and viewport"viewport"= only update the Nlview viewport, but take the schematic from the previous history state."other"= update neither the Nlview schematic nor the viewport; take them from the previous history state instead.