"Sun symbol" on onscreen keyboard

[mgmueller]

When logging in and on some other instances, the smiley symbol on the keyboard is replaced by something looking like a "sun".
Picture attached.
Does anyone have any idea, what to make of this key?

 

[mgmueller]

...just received the answer in another forum:
The "sun" hides the flashing of the keys when entering passwords. So it's harder to guess the password for someone looking over your shoulder.

 

[oion]

Learn something new every day.