Starting to use Eclipse 2018-12, the code preview flyout from content-assist has an unreadable foreground/background combination as in the following screen shot:
I found the Appearance->Color and Fonts->Content Assist preference, but this only takes care of the right part shown above with the white backgrond. (Similarly, if I hover over an element in the editor, the tooltip is also some unreadable dark color on black background.)
This is on Ubuntu. In my active theme I find
@define-color theme_tooltip_bg_color #fbeaa0;
which is clearly not black. The hint about tooltip comes from some of the ultra-old answers like https://superuser.com/a/198589/345087, https://stackoverflow.com/a/38135826/2954288, https://stackoverflow.com/a/3572010/2954288, https://askubuntu.com/a/101913/367444, but these don't seem to apply anymore.
Does anyone know how to fix this with the most recent Eclipse release?
EDIT: I should add that the black window is shown only for Template Proposals Java/Java Type/Java Non Type Proposals are all good.