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.

this.downloadManager?.openOrDownloadData(
      this.container,
      this.content,
      this.filename
    );
  }
}
/**
 * @typedef {Object} AnnotationLayerParameters
 * @property {PageViewport} viewport
 * @property {HTMLDivElement} div
 * @property {Array} annotations
 * @property {PDFPageProxy} page
 * @property {IPDFLinkService} linkService
 * @property {IDownloadManager} downloadManager
 * @property {string} [imageResourcesPath] - Path for image resources, mainly
 *   for annotation icons. Include trailing slash.
 * @property {boolean} renderForms
 * @property {boolean} [enableScripting] - Enable embedded script execution.
 * @property {boolean} [hasJSActions] - Some fields have JS actions.
 *   The default value is `false`.
 * @property {Map<string, HTMLCanvasElement>} [annotationCanvasMap]
 */
class AnnotationLayer {