Running GDM and GNOME on OpenSuse Tumbleweed, I encounter a problem when
entering characters ^, ¨, ~, ` or ´ in the GNOME password prompt such as during
login or when I execute programs requiring root privileges on the command line.
I have leanrt with the help of the OpenSuse Forum that all of these keys are
entered using dead-keys in the Swedish keyboard layout and we have determined
that this is probably a bug. You can find more information under this link:

https://forums.opensuse.org/t/cannot-type-tilde-character-in-gnome-password-prompt/179954/13

I don't encounter the same issue with other keyboard layouts such as the German
or English layouts. My current workaround is to switch to one of these layouts
for the password prompt or enter the character in question using the onscreen
keyboard. Another fix seems to be to set the keyboard variant with the
"nodeadkeys" option as suggested by arvidjaar in the forums:

tw:/usr/share/X11/xkb # localectl --no-convert set-x11-keymap se "" nodeadkeys
tw:/usr/share/X11/xkb # localectl 
System Locale: LANG=en_US.UTF-8
    VC Keymap: us
   X11 Layout: se
  X11 Variant: nodeadkeys
tw:/usr/share/X11/xkb # 

I have not been able to verify this workaround for now, but will try it later
today.

It would be nice if this was fixed properly in the right place, but I have
lived with this situation for a few months and I can use my system without a
fix for now.