arx 自動鎖定文檔類 AcAxDocLock

// When appending entities to a database from the session context,
// AutoCAD requires the following be true to properly append and
// display the entities:
//
// 1. The document is locked
// 2. The document context is current
//
// The document for a database needs to be locked before any write
// operation is performed. Since, AutoCAD has graphics information
// in a per document basis. The document context for the database
// must be current during the creation of any new entities. This
// will guarantee the graphics are updated correctly.
//
// Document activation is disabled to deal with the possibility that
// a user could attempt to activate another document while a local
// COM client is in the process of appending a new entity.