beginCreateItem method
void
beginCreateItem()
Puts the list into a state ready to create a new item. Atomically collapses any expanded rows so that the transition from an expanded-item view to the create form happens in a single state emission — no intermediate "both expanded and creating" frame, no dim-opacity flash, and no collapse-then-reopen flicker in side-panel mode.
Implementation
void beginCreateItem() {
updateState(
who: 'beginCreateItem',
isCreatingItem: true,
clearActive: true,
expandedKeys: createEmptyKeySet(),
);
}