Subject: bug#75930: 30.0.92; Setting default frame background color messes up mouse pointer

From: Lars Rustand <[email-masked]>
Date: Wed, 29 Jan 2025 17:36:18 +0100

Starting Emacs with the --background-color argument results in the contour
of the mouse pointer being set to that color when it is hovering over
Emacs.

This also happens if setting the background color through
default-frame-alist in early-init.el.

Setting the background color on startup through either
initial-frame-alist or window-system-default-frame-alist works as
expected, and does not change the mouse pointer.

Changing the background color of the frame at a later time, either by
calling set-background-color or by loading a theme does not change the
mouse pointer, whether that mouse pointer has already been modified by
Emacs during startup or not.

I am able to reproduce the behaviour in a clean Emacs using -Q.

The easiest way to reproduce is through this command:

    emacs -Q --background-color "#ff0000" --eval '(set-background-color "#000000")'

The results of the above command will be an Emacs frame with a black
background, and the mouse pointer will have a red contour when hovering
over that frame.