Subject: 28.0.50; choose-completion fails

From: Madhu <[email-masked]>
Date: Wed, 14 Apr 2021 10:33:08 +0530 (IST)

In GNU Emacs 28.0.50 (build 2, x86_64-pc-linux-gnu, Motif Version 2.3.8, cairo version 1.16.0)
 of 2021-04-14 built on maher
based on master 844b8949a71f180d395a237c768b22d91cf91ded
(with the motif revert reverted)

1. emacs -Q -eval '(setq pop-up-windows nil pop-up-frames t)'
2. C-x b TAB

this would pop up a new *Completions* buffer in a new frame
with are two choices *Messages* and *scratch*

3. choose a completion (click or hit enter on one of the choices)

user-error: Cannot switch buffers in minibuffer window