Signature placed incorrectly

[ondras]

Configuration:

• Firefox 51
• top_posting: true,
• sig_below: false,
• plaintext editing

When replying to an e-mail, the signature is inserted below the cited text. I believe that the culprit is https://github.com/roundcube/roundcubemail/blob/master/program/js/editor.js#L539, as the get_caret_pos function returns a large number that corresponds to the end of the message. Both setlectionStart and selectionEnd DOM properties of the <textarea> node are the same (equal to .value.length), meaning the caret is collapsed to the end of the text area.

Why does this code path even respect caret position? I would expect the settings above to result in sig being always inserted at the top...

[alecpl]

Sounds like a duplicate of #5628.