Middle-click paste into a "Reply…" input does not work

Summary

When responding in discussion, a middle-click does nothing until input is clicked with left click.

Steps to reproduce

1. Start a discussion

2. Select some text

3. Middle click into the input field

4. Nothing happens.

5. Left click - editor expands:

6. Middle click works now:

What is the current bug behavior?

It is neccessary to expand the editor with a left click first. It is annoying.

What is the expected correct behavior?

The middle click should work in step 3, i.e. without expanding the editor.

Possible fixes

Just make sure the <textarea> is there and working, even if it is grey.