Na to je u Common Controls buttonu (t.j. u klasickeho buttonu aky vo Win existuje) flag "BS_PUSHLIKE" (http://msdn.microsoft.com/en-us/library/bb775951(VS .85).aspx). Nema Ten TButton nahodou takyto flag? Ukazka ako to funguje:
http://blogs.msdn.com/oldnewthing/archive/2007/09/2 1/5021765.aspx
... t.j. pouzijes nejaky checkbox (TCheckbox?) a nastavis mu BS_PUSHLIKE. Ak to teda v Delphi ide. Ak nie tak zahod delphi