missing image in "Custom Inline Controls" demo

[nitroamos]

While browsing to figure out what kind of dropdown I want to use, I saw this from the showcase:
https://www.smartclient.com/smartcli...izeIncrease=10
the checked image when the click is held is missing.



it's labeled:
https://www.smartclient.com/smartcli...prove_Down.png

isc.version
"v11.1p_2017-10-09/AllModules Development Only"

I don't need this urgently for myself.