Description

This function detect if another copy of application is running

Delphi code

Function IsRunningApp:Boolean;
var
    Hwnd:Thandle;
begin
    hwnd:=CreateMutex(nil,False,'OneCopyMutex');
    Result:=false;
    If not(WaitForSingleObject(Hwnd,0)<>Wait_TimeOut) then
    Result:=true;
end;