resetFor method
Forgets what the previous entry's shell declared.
Called from the guest when the entry changes, so that an entry whose wrapper is not a shell reports having no axes immediately, rather than leaving the last shell's on the bar until something replaces them. Selections are untouched — they belong to the shell, which is what makes them survive an entry change.
Implementation
void resetFor(String entryId) {
if (_entryId == entryId) return;
_entryId = entryId;
_shellId = null;
_declared.clear();
}