THPDFHeadlessOptionalContentState.Selection
function Selection(Index: Integer): THPDFOptionalContentSelection;
返回一个从零开始的手动选中项副本;索引超出 SelectionCount 抛出 EHPDFOptionalContentStateError
function Selection(Index: Integer): THPDFOptionalContentSelection;
返回一个从零开始的手动选中项副本;索引超出 SelectionCount 抛出 EHPDFOptionalContentStateError