Attach (recommended) or Link to PDF file [here:] Can't see how to attach a pdf here, but it is simple to create. Add a form object textbox to a pdf and make sure the option for "Multiline" is true.

Steps to reproduce the problem:
1.  Open a document with a Textbox that is set to Multiline.
2. Attempt to hit the Enter key to go to a new line.

What is the expected behavior? The cursor goes to a new line.

What went wrong? It does not go to a new line.

Link to a viewer: It can be reproduced on mozilla.github.io/pdf.js

I corrected the issue by altering the pdf.js file like this
element.addEventListener("keydown", event => { 
[...]
--} else if (event.key === "Enter") {
++ } else if (event.key === "Enter" && !this.data.multiLine) {

Our initial testing is coming through clean, and hopefully something like this code can be committed to the project in the future.

if (!annotationCanvasMap) {
      return;
    }
    for (const [id, canvas] of annotationCanvasMap) {
      const element = div.querySelector(`[data-annotation-id="${id}"]`);
      if (!element) {
        continue;
      }
      const { firstChild } = element;
      if (!firstChild) {
        element.append(canvas);
      } else if (firstChild.nodeName === "CANVAS") {
        firstChild.replaceWith(canvas);
      } else {
        firstChild.before(canvas);
      }
    }
    annotationCanvasMap.clear();
  }
}
export { AnnotationLayer };