Download attribute in Anchor tag inside a iframe is not working in IE11


Description

Under activity stream/Chat, when user clicks on the attached file, a popup with a download icon will appear. In IE 11 when the download icon is clicked, it is opening a new blank browser window and not downloading the attachment. It works as expected in Edge and other browsers.

Steps to Reproduce

1) Login using IE 11
2) Attach an image file to an incident and copy the URL of the same incident
3) Create a UI page which contains the following iframe and uses the incident URL(mentioned in step 2)

<?xml version="1.0" encoding="utf-8" ?><j:jelly trim="false" xmlns:j="jelly:core" xmlns:g="glide" xmlns:j2="null" xmlns:g2="null"> <h1>Hello world </h1><iframe frameborder="0" style="height: 100%; width: 100%;" scrolling="no" id="chatframe" src="<INCIDENT URL mentioned in step 2>" name="chatframe" sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-downloads-without-user-activation" ></iframe></j:jelly>

4) Load the UI Page
5) Go to the activity stream and click on the attached image - users will be provided with a popup that has a small download icon at the rightmost bottom.
6) Click on the icon (mentioned in step 5)

Actual behavior - A new tab is opened and the image is not downloaded
Expected Behavior - It shouldn't open a new tab and download the attached image

Workaround

After carefully considering the severity and frequency of this problem, and risk of attempting a fix, it has been decided to not address this issue in any current or future releases. We do not make these decisions lightly, and we apologize for any inconvenience.


Related Problem: PRB1361139