bug#47766: 28.0.50; choose-completion fails

[Alan Mackenzie]

Hello, Madhu.

I've been looking into this bug for several hours, and it may take some
while to fix.  Thanks for taking the trouble to report it.

On Tue, Apr 20, 2021 at 08:25:13 -0500, Stefan Kangas wrote:
> Gregory Heytings <gregory@heytings.org> writes:

> >> 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

Gregory and Stefan:

> > This is because of commit 7c2ebf6e23.

> Copying in Alan here.

Thanks for drawing my attention towards the bug.

-- 
Alan Mackenzie (Nuremberg, Germany).