Installed a GNU Guix 1.5 as an OS in QEMU. I went into MATE, checked the box to show seconds on the clock, and added my local Seattle weather. The panel instantly died, and started an infinite loop of rapidly respawning and crashing, causing all the desktop icons to violently vibrate up and down. Apparently, functionally evaluating the concept of "rain in the Pacific Northwest" results in a fatal mathematical error. I like my stable distros.