Specifies group index that is used to filter ext ranges in the syntax tree view.
property GroupIndex: integer;
GroupIndex is used to filter text ranges in TSyntaxTreeView.
Text range will be added to the syntax tree view, if
DisplayInTree and (GoupIndex = 0 or TSyntaxTreeView.GroupIndex = 0 or (GroupIndex and TSyntaxTreeView.GroupIndex <> 0)).
Intersection of group indexes allows to enable several groups at a time.