Sample code which creates control with two tabs:
t:= TATTabs.Create(Self);
t.Parent:= Self;
t.Align:= alTop;
//optional event handlers
t.OnTabClick:= {$ifdef FPC}@{$endif} TabClick;
t.OnTabPlusClick:= {$ifdef FPC}@{$endif} TabPlusClick;
t.OnTabClose:= {$ifdef FPC}@{$endif} TabClose;
//add tabs
t.AddTab(-1, 'Tab one');
t.AddTab(-1, 'Tab middle len', nil, false, clGreen);