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Two Lists synchronised movement

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Alongside each other on a form I have a CheckList and a ListBox. As I scroll down the CheckList (on the left side) box I want the ListBox (on the right side) to also scroll down, but at half the speed. The left side has 64 rows (col height 30)  , the right side 32 rows (col height 60).  As the scrolling goes through the 64 rows on the left side two rows at a time I want the right side to scroll down one row at a time. The application monitors progress of a knockout competition.


Currently I try this using the following procedures to synchronise the vertical scrolling:


procedure TForm1.Grid1WindowProc(var Message: TMessage);
  if ((Message.Msg = WM_VSCROLL)) then OldGridProc2( Message );

procedure TForm1.Grid2WindowProc(var Message: TMessage);
  OldGridProc2( Message );
  if (( Message.Msg = WM_VSCROLL )) then OldGridProc1( Message );


In the form activate I have this:

OldGridProc1:= sgLastRound.WindowProc;  

sgLastRound.WindowProc := Grid1WindowProc;
OldGridProc2:= gsgNextRound.WindowProc;

gsgNextRound.WindowProc:= Grid2WindowProc;


And this works correctly scrolling each side BUT at the same amount. What I'm after is the right side to scroll at half the amount of the left side. I can't see where I can divide the right side movement by 2 so it goes half the distances. Sorry if this isn't that clear. The attached screenshot may help visualise the problem.


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Why not just set the absolute scollbar position of the listbox based on the position of the checklist scrollbar position?

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How about using buffer items in second--These would be blank or ad space :)--but stay at 30 for height unless there is a way to insert a 15 height buffer first to center second items displays.   


TWinStatus = (WSallin,WSsecondround..WSoverallwinner)

TTeam = record
   name: string;
   Lastwin: TwinStatus
Winners: Tlist;

Teams: tlist;
//build the controls.items at runtime
 round := WSallin; 

//add half height dummy to second list if possible
with Teams do
  if TTteam(items[ii]).Lastwin := round then add to listbox1.items
  if TTteam(items[ii]).Lastwin := TwinStatus(round + 1) then 
    add to listbox2.items
    add dummy to listbox2.items


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