you can always use the default smilies page in a popup:
https://vborg.vbsupport.ru/misc.php?do=smilies
the problem is when you post... the popup is tightly related to the post you're making... you can't leave the popup opened after the post is made because the script have to be related to the post field to make sure it sends the smilies code in the right place... that's why it closes when the post is sent... each post have a different ID that the script detect...