I am seeing this too. It seems to be particularly when the combination of screen size and magnification results in division by or multiplication by half.
For example:-
Editing a layout of 1024x600x1 or 1280x800x1 both seem to be free of the problem. However, if I do 800x1280x1 I need to switch ZOOM to 50% in the Abstract Designer Window to see what I am doing and this then causes unexpected behaviour, most usually the TOP or LEFT value for a view decreasing by one when that view is selected. I could understand it going wrong when I try to drag a view around the designer screen, but not when I just click on it.
The same thing seems to happen sometimes when the native density is 1.5, 480x800x1.5 can cause similar problems.
There also seems to be a problem with dragging whilst ZOOM is set to 50%. I would expect to be able to position a view to the nearest 10 pixels at 50% (in other words 5 pixels on the screen is the 10 pixel grid for normal viewing), just as I can at 100%, but this doesn't seem to be the case.
In other regards the Abstract Designer is a joy to use and very quick to work with, just gets a little (lot) annoying at times. It can be worked around with a bit of typing of values, but is less than ideal.
David