Illustrator: Problems with Align to pixel grid

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Problems with “align to pixel grid”

The “Align to pixel grid“ setting, which is on for some New document profiles, still causes irritation. This is a collection of problems caused by the feature. I strongly guess, that this list isn't complete.

Reshaping of objects when applying strokes
This is probably the most frequent phaenomenon: graphics get distorted, when a stroke is applied or taken away. People like to demonstrate this in videos, interchanging a fill of none and a stroke about 5 times to completely destroy an object like this star.
Reshaping when aligning the stroke
Objects also get distroted when a stroke is aligned from the center to the inside or outside or vice versa.
Stroke can only be applied in whole-numbers
The stroke panel shows only whole-numbered point-values after entering a fractional value and of course applies these to the graphic. In case you set the preferences “unit” for stroke to something different than points, you could even get something more quaint.
No exact movement
Objects can only be moved into positions at the edges of pixels, not to the place you want them to be.
Gaps between stroke and fill when applying the rounded-corner-effect
Like so:
Objects arent aligned to the center
In case the difference between their width resp. heights is an uneven value, objects cannot be center-aligned.
Pathfinder functions don't produce clean results
For instance when applying the pathfinder “Outline“, the resulting anchor points don't align exactly. The figure shows the expected result on the left (without “align to pixel grid“) and a wrong result on the right.
The shapebuilder tool desn't produce clean results
With “align to pixel grid“ on, the shapebuilder tool produces rather blotted results.
Alterations when outlining strokes
Of course when applying “outline stroke” orr “Expand” you'll have to expect blotted results as well.
Mysterious partial inversion of paths
When “align to pixel grid” is applied to the shape on the left, it will be changed to the shape on the right.
Stroke shifts when aligned to the inside/outside of path
When an object is already aligned to the pixel grid, its stroke will shift again after being aligned to the inside or outside via the buttons in the stroke panel. The path will not be affected that way.
Guides aren't placed exactly where you moved them.

See other English tutorials:

Proposals for better better workflow in Illustrator
3D-Animation
Freeform-artbrush with a gradient
Stylish guilloches with gradients
Outline object and outline stroke
Aligning and distributing - Special