Dialog position flip doesn't work when pass coord manually

Forgot to say, that if you change the collision to 'flipfit flipfit' then it works.

Can you please explain what you're trying to achieve? Based on the fiddle, its not clear to me.

Here's a cleaned up fiddle, using the HTML and JS panels as intended: https://jsfiddle.net/9ds4c5yg/

Sorry for my late reply, I thought it would notify me by email if someone replied.

So, in the example, I'm trying to open a dialog giving the coordinates of the right side of the screen, and I expect that it would flip the dialog horizontally without creating an x-scrollbar.

With these positioning instructions, flipping will still not result in the dialog being more visible, so it won't flip. You should never use flip collision on a dialog anyway. Always use fit or flipfit (fit is likely your better option).

But then how about this scenario: https://jsfiddle.net/9ds4c5yg/2/ Here I've put an element, and used it as a target, and it has flipped, so there is no x-scrollbar anymore.

Because flipping in that case makes the dialog more visible than not flipping.

Exactly, and in the first scenario (https://jsfiddle.net/9ds4c5yg/), where I put the same coordinates manually, it should also be the case, but instead it is creating an x-scrollbar.

I don't think you understand how flipping works. Everything is flipped, including your offset. Notice in the second example that the meaning of left and right is inverted for both values. If you still need clarification, please use the forums, Stack Overflow, or IRC.