This also happens with TDE desktop with one slight difference. Instead of a bunch of complete "row" tooltips I get a bunch of fragments of "row" tooltips. This has been annoying me for a very long time.
Thank you to Torbjörn Andersson <eriktorbj...@telia.com> for the workaround. Turning on Composite Extension in Xorg made no difference but doing that and then enabling the Trinity Window Composition Manager does clean up the mess. It appears that LibreOffice calc assumes compositing is enabled even when it is not. --Mike