Unexpected results for StrokeLine with pen sizes != 1

[madmax]

This is the result of StrokeLine(BPoint(x, y), BPoint(x, y+6)) with pen sizes 1, 2 and 3 (same behaviour for greater even/odd sizes), x and y being integer values:

This may be a bug, a mismatch between documentation and real BeOS, or just a misunderstanding on my part, but I would expect that:

• all lines be the same length (the one for pen size 1, with 7 pixels lit)
• there'd be no antialiasing on the edges

Horizontal lines have the same effects.

With B_SUBPIXEL_PRECISE we also get different lengths. The AA in the edges disappears, but I'm not sure the one along the line is correct:

Shouldn't the half pixels show for even widths when centered on a pixel and for odd widths when offset half a pixel?