When you did customize your Access Gateway theme, you might have this error trying to logon on the admin page of your Netscaler. No worries there is a simple solution to fix it. Never the less, you need to remember to change your Access Gateway theme customization back to default prior performing a Netscaler upgrade.
What I like when I access my virtual desktops and applications is consistency thought different systems, front web and UI... Citrix have try with the green bubble theme to bring this but that wasn't really a success due to this "not very good looking" theme :)
Storefront is evolving and Citrix is finaly out of the green bubble template with a soft and neat design for this Technology Preview. Storefront X1 (aka v2.7) Here is a short list of what Citrix envision for this and the upcoming release