Moving 'group' not pixel perfect
 

I wanna move a 'group' element. When I start moving, it moves perfectly pixel by pixel. However, at one point, it insist on jumping from y:559 to y:563. Before that, it works pixel by pixel.

What is causing this behaviour, and how to move pixel by pixel?

Also, the same 'group' element is moving in x direction by 2 pixels. How to disable this?

I have disabled "snap to grid" checkbox.

I'm totally new to OG and using yahoo iphone stencils.

Solved: Arrange->Guides->Smart guides off