WindowProc überschreiben:
Delphi-Quellcode:
procedure TForm1.Edit1WndProc(var Message: TMessage);
var
Input: Char;
begin
Input := Chr(Message.WParam);
if (Message.Msg = WM_CHAR) and (Input = FormatSettings.DecimalSeparator) then
Edit1.SelText := Input
else
FOldEdit1WndProc(Message);
end;