Selects whether all collapsible layer legends are collapsed.
Non-collapsible leaf layers are considered inherently collapsed (nothing to expand), so they do not prevent this from returning true.
True if all collapsible legends are collapsed, or if there are no collapsible layers
Selects whether all collapsible layer legends are collapsed.
Non-collapsible leaf layers are considered inherently collapsed (nothing to expand), so they do not prevent this from returning true.