The test file at https://github.com/mozilla/pdf.js/blob/master/test/pdfs/annotation-choice-widget.pdf contains listboxes, which are not rendered correctly when printed right now. These kinds of fields are made by https://github.com/mozilla/pdf.js/blob/master/src/display/annotation_layer.js#L672-L678.

/cc @calixteman 
if (this._buttonCaption) {
      return this._buttonCaption[nFace];
    }
    return "";
  }
  buttonGetIcon(nFace = 0) {
    if (this._buttonIcon) {
      return this._buttonIcon[nFace];
    }
    return null;
  }
  buttonImportIcon(cPath = null, nPave = 0) {
    
  }
  buttonSetCaption(cCaption, nFace = 0) {
    if (!this._buttonCaption) {
      this._buttonCaption = ["", "", ""];
    }
    this._buttonCaption[nFace] = cCaption;
    
    
    
    
  }
  buttonSetIcon(oIcon, nFace = 0) {