textedit windows grays out obscuring text

yoelf wrote:

This happens with sessions that remain long enough on my mbpro, surviving hibernation (lid closed)

Part of the window is grey out, and text is illegible.

It is selectable, though, and once I select all content, the text displays.

Macbook pro 2015 Retina, Catalina 10.15.4

Reboot as a trouble shooting first step.

If you continue to have an issue—To trouble shoot further you can:

Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Login and test. Reboot and test as caches get rebuilt.

This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

Test issue in another user (or guest user) account  https://support.apple.com/en-us/HT204443

This will tell you if it a universal issue or isolated to your user/admin account.