Fabio,
Your "bug" only is visible for very narrow column widths. Any column with a few characters in the Header.Caption to describe what the column is would require the enduser to put a ruler up to the screen to quantify the couple of pixel difference between the left and right margins.
If your column is that narrow why not simply left align the chk and and make the column width the exact amount it would take toe "center" the checkbox.
>it is a bug.
>
>read Thread #
801170.
>
>Set column width to 50, and reduce it.
>Right font space ( the bug ) is computed on centered alignment;
>it is perceptible only with width near to 20 pixel.