zwei Checkboxen verknüpfen

[Matze]

Das musst du halt nur auf deine CheckListboxen übertragen, drüfte aber kein Problem sein.
Das ist das, was Jens gemeint hat.

Delphi-Quellcode:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    ListBox2: TListBox;
    procedure FormCreate(Sender: TObject);
  private
    { Private-Deklarationen }
       OldGridProc1, OldGridProc2: TWndMethod; 
   procedure Grid1WindowProc(var Message: TMessage);
   procedure Grid2WindowProc(var Message: TMessage);
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Grid1WindowProc(var Message: TMessage);
begin 
  OldGridProc1(Message); 
  if ((Message.Msg = WM_VSCROLL) or (Message.Msg = WM_HSCROLL) or
      (Message.Msg = WM_Mousewheel)) then
  begin 
    OldGridProc2(Message); 
  end; 
end; 

procedure TForm1.Grid2WindowProc(var Message: TMessage); 
begin 
  OldGridProc2(Message); 
  if ((Message.Msg = WM_VSCROLL) or (Message.Msg = WM_HSCROLL) or 
     (Message.msg = WM_Mousewheel)) then 
  begin 
    OldGridProc1(Message); 
  end; 
end; 

procedure TForm1.FormCreate(Sender: TObject);
begin
  OldGridProc1 := ListBox1.WindowProc; 
  OldGridProc2 := ListBox2.WindowProc;
  ListBox1.WindowProc := Grid1WindowProc;
  ListBox2.WindowProc := Grid2WindowProc;
end;