[Lazarus] TMemo flicker

[K. P.]

Have you tried wrapping your writes in memo1.Lines.BeginUpdate and memo1.Lines.BeginUpdate?
 > Date: Mon, 29 Apr 2013 18:34:07 +0200
> From: juergen.hestermann at gmx.de
> To: lazarus at lists.lazarus.freepascal.org
> Subject: [Lazarus] TMemo flicker
> 
> After having moved from TStringList over TStringGrid (which both cannot be shifted right to make long text visible) I now use TMemo. But again I have another issue with this component: If there are more rows than can be displayed in the window and I change the text in the last row (Lines.Count-1) rapidly then the whole display flickers. This OnClick event demonstrates it:
> 
> -------------------------------------------------------
> with Memo1 do
>     begin
>     for i := 1 to 40 do
>        begin
>        if odd(i) then
> Append('\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\')
>        else
> Append('+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++');
>        end;
>     for i := 1 to 1000 do
>        begin
>        Lines[Lines.Count-1] := '#### LAST LINE ---'+IntToStr(i)+'-----------------------------------------------------------';
>        Application.Processmessages;
>        end;
>     Memo1.Lines[Lines.Count-1] := '#### READY #### ';
>     end;
> -------------------------------------------------------
> 
> When you click on the memo (so that the routine runs) and the window is small enough then all lines are shifted down for a short time and then are shifted up again when writing to Memo1.Lines[Lines.Count-1]. This flicker is quite disturbing and it does not happen when there are only a few lines (which fit in the window). Is this a known bug?
> 
> 
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