Drag-andDrop setDragImage offset ambiguities

[jabcreations]

What is the issue with the HTML Standard?

Only Gecko browsers honor the offset coordinates for setDragImage and only on the first instance. Otherwise all rendering engines ignore the offset and do whatever they feel like which is a major visual issue when it comes to drag-and-drop.

There are two ambiguity issues with the specification:

1. The word offset isn't even used! This likely resulted in developers of rendering engines basically ignoring the offset which is a bug in all browsers as of April 2026.
2. The offset is just a "long", a long what? Is it a percentage? We presume it's the number of pixels though the point of having standards is to nullify ambiguity.