CIFGenSubcells() and extSubtree() set GrDisplayStatus =
DISPLAY_IN_PROGRESS while they run a 5-second progress timer, then
unconditionally restore DISPLAY_IDLE on exit. In native builds the
initial state is always IDLE, so this is harmless. In WASM/headless
builds the null display driver sets DISPLAY_SUSPEND at startup, and
forcing IDLE at the end of these long operations destroys the
SUSPEND guard that protects WindUpdate() from running display
callbacks against a non-existent screen.
Save the previous status before overwriting and restore it on exit.
This is also reentrant-safe: nested DISPLAY_IN_PROGRESS scopes (e.g.
extract followed by gds write) now keep the outer state intact.
* cif/CIFhier.c — CIFGenSubcells
* extract/ExtSubtree.c — extSubtree
b74b1f936a