Flash movieclip position issue

Very strange issue: imgLoader0_mc (e.target.parent) is a movieclip load开发者_开发百科ed with an external JPG. ImageMark is a movieclip with the same dimensions (w and h) of imgLoader0_mc and the same registration point (top left): I verified this many times. They both are in the same container and each of them is under a mask.

At some point I have:

this.imageMark.x = e.target.parent.x;
this.imageMark.y = e.target.parent.y+0.4;

The question is: why that 0.4? While the x is right, Flash for no apparent reason positions imageMark in a wrong way: adding that 0.4 eliminates the problem but I don't understand why this happens (and, without adding 0.4, if I trace the position of e.target.parent and imageMark it is the same... but it isn't...)...

By default, flash will position a stroke straddling the coordinates of the stroked shape. For example, if you have a rectangle at 10, 10 that is 10 x 10 and has a two point stroke, the stroke will start at top left of the stroke will be at 9, 9, and the bottom right will be at 11, 11.