Capture Maximize/Minimize/Close button clicks

...

type

TForm1 = class(Form)

...

public

procedure WMSysCommand(var Msg: TWMSysCommand); message WM_SYSCOMMAND;

...

procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);

begin

if Msg.CmdType = SC_MINIMIZE) or (Msg.CmdType = SC_MAXIMIZE) or (Msg.CmdType =

SC_CLOSE) then

...

else

DefaultHandler(Msg);

end;