Make anchor snap to window side

[brainwo]

Out-of-bound cut-off anchor doesn't look great. Anchor should stay within the visible canvas.

Here's an illustration of what I mean:

[Xazin]

Good catch

[brainwo]

This might be related to this issue, perhaps this proposal is a good solution for this too:

As you can see, the anchor is cropped within the scrollable which I would argue looks ugly.