ecSyntMemo.pas
1.window update on holding PgUp/PgDn keys.
in block
      smPageUp:      begin
                       x := ScrollPosY;
                       ......
                       .....
                     end;
add Update at end:
      smPageUp:      begin
                       x := ScrollPosY;
                       ......
                       .....
                       Update;
                     end;

2.in the same code make VisibleLines function used only once.

3.update on scrollbar thumb dragging.
procedure TCustomSyntaxMemo.WMVScroll
add "Update;" call at end.
