This question already has an answer here:
When writing a question or answer, I usually include a couple of links to outside resources. When I do the following:
- Insert an image using 'Insert image/provide a link from the web'. Paste hyperlink into the dialog. Dialog closes.
- Insert a hyperlink into the edit box. test link
step 2 fails: I can't paste anything into the Hyperlink dialog box. From that point on, I can't past into the answer box either. I have to post the answer, then click Edit, then I can paste again.
This happened when writing this question. In the edit history you should be able to see 2 revisions, where the first revision has an incomplete hyperlink (2).
OSX 10.10.5/Firefox 56.0 (I've also seen this on Windows 7/Firefox)