Problems with Thunderbird-115 in Slackware64-current

The attached screenshot shows two problems. One, note the "shadow border" around Thunderbird and, two, the printing problem. This is the first time I've ever had a printing problem with Thunderbird. The box, as you see it in the image, pops up and the circle keeps spinning, i.e., that print job is never sent to the printer. And, now, the same problem exists with Firefox. No printing problems with Vivaldi or LibreOffice.
Having trouble uploading the image. The board is telling me I don't have permission to access "this page."
Whatever......