Description of problem:
According to a fedora Testcase_realmd_gdm_screen[1] there should be a hint as how to type a domain user in GDM when the computer is joined to a realm. The help should be shown after choosing "Not Listed?" option but there is no such help.

[1] https://fedoraproject.org/wiki/QA:Testcase_realmd_gdm_screen

Version-Release number of selected component (if applicable):
gdm-3.14.2-18.el7.x86_64
adcli-0.8.1-3.el7.x86_64
sssd-1.14.0-30.el7.x86_64
samba-libs-4.4.4-9.el7.x86_64

How reproducible:
always

Steps to Reproduce:
https://fedoraproject.org/wiki/QA:Testcase_realmd_gdm_screen


Actual results:
There is no hint how to type a domain user.

Expected results:
There should be hint how to type domain user.

Additional info:
During the realm join it appears when the "Not listed?" option is selected, but when you click cancel and try the "Not listed?" option again it is not there.