Write OnGetStyleList event handler to apply custom highlighting styles. For example, you may highlight error words, perform custom dynamic highlighting and so on. 

CurPos specifies current position at which styles are retrieved. If there are some styled regions that contain CurPos, you have to create and fill instance of TStyleEntry and add it to StyleList. 

Set NextPos to:

1. End position of selected styled region, if it contains CurPos;
2. Start position of the nearest styled region that follows after CurPos;
3. -1, if there is no styled regions after CurPos.

TSyntaxMemo Properties