This event is fired when Windows messages are to be handled.
This event is fired by TElSftpClient when the component is in
synchronous mode and needs to process Windows messages. Depending on the architecture of your socket communication (synchronous or asynchronous) you can either process some messages from the message queue or just call Sleep(0) or do nothing. Return true if SFTP client can continue or false if blocking operation must be stopped.
Use this callback function if you wish to process all incoming messages yourself while TElSftpClient waits for synchronous server response. If this property is set to nil (null, Nothing), TElSftpClient uses its internal message loop to peek and dispatch messages.
Note, that this callback should be handled only if SynchronousMode property is set to true.