updateGroup method
Updates a whole selection group at once (colour, kind or note).
Implementation
void updateGroup(String groupKey, {UDocMarkupKind? kind, Color? color, String? note}) {
bool changed = false;
for (int i = 0; i < _markups.length; i++) {
if (_markups[i].groupKey != groupKey) continue;
if (!changed) _checkpoint();
changed = true;
_markups[i] = _markups[i].copyWith(kind: kind, color: color, note: note);
}
if (changed) _commit();
}