Please add python3_9 to x11-wm/openbox. Simply adding python3_9 to PYTHON_COMPAT to the =x11-wm/openbox-3.6.1-r3 ebuild works here.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=c041c9a6d1228503e15329e7eaffb24dc49c9b5b commit c041c9a6d1228503e15329e7eaffb24dc49c9b5b Author: Andreas Sturmlechner <asturm@gentoo.org> AuthorDate: 2021-03-13 23:57:00 +0000 Commit: Andreas Sturmlechner <asturm@gentoo.org> CommitDate: 2021-03-14 23:01:53 +0000 x11-wm/openbox: Fix IUSE=-xdg w/o python, drop 'static-libs', py39 Closes: https://bugs.gentoo.org/772878 Package-Manager: Portage-3.0.17, Repoman-3.0.2 Signed-off-by: Andreas Sturmlechner <asturm@gentoo.org> x11-wm/openbox/openbox-3.6.1-r3.ebuild | 38 +++++++++++++++++++--------------- x11-wm/openbox/openbox-9999.ebuild | 38 +++++++++++++++++++--------------- 2 files changed, 42 insertions(+), 34 deletions(-)