>>It's not a bug. Your assumption that shape is centered horizontaly from the beginning is incorrect.
>
>Where I have written this ???????

DEBUGOUT "start centered", ...

>
>>The shape center is one pixel closer to the top border of the form than to the bottom.
>
>Sergey, please,
>run the code with NNHEIGHT 1, 2 and 3, 4
>With 2 it is ok,
>with 1 it is not moved
>with 3 it is moved to a incorrect position
>with 4 it is correct
>......

It's moved to the correct position according to Anchor = 512 and original position of the shape center. The problem is that center of the shape with odd height is 1 pixel closer to it's top border than the bottom one.