Steps to reproduce:

1. Go to a talk page (Make sure DiscussionTools is enabled)
2. Click on Reply to any comment
3. When the Reply tool opens up, click on the Special Character insert option on the toolbar

Observed Result:
Special Characters menu is opening up on top of the comment box in reply tool on talk pages with an odd transition of the entire toolbar.

Expected Result:

I think It used to open up over the reply tool comment box, just how it opens anywhere else inside VisualEditor. For example:

Browser: Chrome

Wiki: en.wiki

Environment: Production