I've been calculating the number of .25mm optical fibers required to fill a 25.5mm diameter collar.
By making a matrix of .25mm circles, I have covered a 25.5 mm circle.
Attempting a selection of the small circles extending beyond the big circle, the multi-sided selection marquee also selects small circles extending beyond the selection marquee by a factor of three of four extra circles.
It is like there is a minimum selection area similar to 'gravity'.
I think Archicad has trouble with minute accuracy. Recently I have been drawing some components for light fittings that require fractions of a millimeter (for ""laserrr"" cutting) and I often have to enlarge the pieces by a factor of 10 to be able to draw them accurately enough.
I just tried it and had no problems. I just made an array of close packed 0.25 mm diameter circles and the marquee tool deleted selections accurately as one would expect with none of the overflow shown in your video.
ArchiCAD does seem to be a bit finicky at sub-mm dimensions. Some dialogs won't accept values less than 1mm. The magic wand setting is one of these. Perhaps this is related to your problem.
Yup. Confirmed. The arrow tool selects a larger range than the area clicked. I just tried it with a plain rectangular selection and the selected elements extend to 1 mm beyond the extents of the rectangle.