SeaMonkey was updated to 2.53.16:

* No throbber in plaintext editor bug 85498.
* Remove unused gridlines class from EdAdvancedEdit bug 1806632.
* Remove ESR 91 links from debugQA bug 1804534.
* Rename devtools/shim to devtools/startup bug 1812367.
* Remove unused seltype=text|cell css bug 1806653.
* Implement new shared tree styling bug 1807802.
* Use `win.focus()` in macWindowMenu.js bug 1807817.
* Remove WCAP provider bug 1579020.
* Remove ftp/file tree view support bug 1239239.
* Change calendar list tree to a list bug 1561530.
* Various other updates to the calendar code.
* Continue the switch from Python 2 to Python 3 in the build system.
* Verified compatibility with Rust 1.66.1.
* SeaMonkey 2.53.16 uses the same backend as Firefox and contains
  the relevant Firefox 60.8 security fixes.
* SeaMonkey 2.53.16 shares most parts of the mail and news code with
  Thunderbird. Please read the Thunderbird 60.8.0 release notes for
  specific security fixes in this release.
* Additional important security fixes up to Current Firefox 102.9
  and Thunderbird 102.9 ESR plus many enhancements have been
  backported. We will continue to enhance SeaMonkey security in
  subsequent 2.53.x beta and release versions as fast as we are able
  to.