Descriptive Problem Summary:
Images seem to jitter when the screen isn't updating and it is at a diagonal angle. This looks like an issue with keeping the last frame of the transformation. I've only encountered this with images.

BYOND's linear interpolation on animate() also seems to be broken (it messes with scale even if you don't), but that's another issue that I've fixed with softcode. Perhaps I'll make another bug report, but it isn't that urgent, and may have been fixed already anyway since I've last tested it.

Numbered Steps to Reproduce Problem:
1. Try to move with the arrow keys, diagonally.
2. If you're not moving yet, the image jitters back into the last cardinal direction.
3. Once you start moving, the image seems to be fine.

Code Snippet (if applicable) to Reproduce Problem:
http://files.byondhome.com/Kamuna/TestCases/ ImageAnimateTest_src.zip

Expected Results:
Smooth interpolation.

Actual Results:
Jitter and backtracking.

Does the problem occur:
Every time? Or how often?
Every time.
In other games?
Yup.
In other user accounts?
Affirmative.
On other computers?
Not sure on this one.

When does the problem NOT occur?

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
It did not occur in 510.1338. Did not test 510.1339, but I assume the whole messing with the transformations thing caused it, so it probably doesn't work in 510.1339 either.

Workarounds:
Set blockerObj's transform to the final transformation angle after calling animate() (example commented out).