OneInst - Problem bei der Übergabe von Parameter

[Mazel]

Ok, ich habe jetzt hier mal die oneinst:

Delphi-Quellcode:

unit OneInst; 

interface 

{ Make a call to this procedure in your project source 
  immediately before the first call to CreateForm. 
  That should ensure it is after the Application.Title 
  assignment that can muck up the logic. 

  If you haven't set an application title yet, then 
  do so to ensure this works } 

procedure EnsureSingleInstance (MyGUID : string) ; 

implementation 

uses 
  WinTypes, WinProcs, Forms, SysUtils, Messages; 

procedure EnsureSingleInstance (MyGUID : string) ; 
var 
  Wnd: HWnd; 
  WndClass, WndText: array[0..255] of char; 
begin 
{$ifdef Win32} 
  { Try and create a semaphore. If we succeed, then check } 
  { if the semaphore was already present. If it was } 
  { then a previous instance is floating around. } 
  { Note the OS will free the returned semaphore handle } 
  { when the app shuts so we can forget about it } 
  if (CreateSemaphore(nil, 0, 1, 
        PChar(MyGUID)) <> 0) and 
     (GetLastError = Error_Already_Exists) then 
{$else} 
  if HPrevInst <> 0 then 
{$endif} 
  begin 
    Wnd := GetWindow(Application.Handle, gw_HWndFirst);  //hier erfahre ich das Handle
    while Wnd <> 0 do 
    begin 
      { Look for the other TApplication window out there } 
      if Wnd <> Application.Handle then 
      begin 
        { Check it's definitely got the same class and caption } 
        GetClassName(Wnd, WndClass, Pred(SizeOf(WndClass))); 
        GetWindowText(Wnd, WndText, Succ(Length(Application.Title))); 
        if (StrPas(WndClass) = Application.ClassName) and 
           (StrPas(WndText) = Application.Title) then 
        begin 
          { This technique is used by the VCL: post } 
          { a message then bring the window to the } 
          { top, before the message gets processed } 
          PostMessage(Wnd, wm_SysCommand, sc_Restore, 0); 
{$ifdef Win32} 
         {meine Abfrage von ParamStr und dann an das erhaltene Handle sendeen}
          If ParamStr(1) <> '' then with MyCopyDataStruct do
           begin
            dwData:=SecondInstID;
            cbData:=Length(PChar(ParamStr(1))) + 1;
            lpData:=PChar(ParamStr(1));
            SendMessage(Wnd, WM_COPYDATA, 0, LPARAM(@MyCopyDataStruct));
           end;
          SetForegroundWindow(Wnd); 
{$else} 
          BringWindowToTop(Wnd); 
{$endif} 
          Halt 
        end 
      end; 
      Wnd := GetWindow(Wnd, gw_HWndNext) 
    end 
  end 
end; 

end.