Crash on reopening window as ACC

[mikrosk]

As reported by @xdelatour here: freemint/teradesk#9 (comment)

Unfortunately I found another one: when launched as accessory, a .hyp can be opened from the Desk menu (via file selector), others .hyp can be loaded by dragging to the window. But after closing the window, a new click in the Desk menu kills Hyp_View.

This happens only with memory protection enabled. Without MP, the window is reopened.