Unable to attach screenshot using paste in Firefox

Summary

When attempting to paste a screenshot into Firefox, using CMD+V it does not automatically bring up the attach screenshot modal / popup. It works as expected with Chrome.

Environment

• OS X 10.10.5
• Firefox 43.0.1

Steps to Reproduce

1. Copy screenshot from Finder.
2. Paste into issue in Firefox.

Expected Results

The attach screenshot modal / popup appears.

Actual Results

Nothing happens.

Workaround

Tested and works using Chrome. Alternatively using Attach screenshot and then pasting in Firefox will work.