First serious customer was Symantec with their Norton Antivirus. Norton AV 2007 was their first version that used Sciter (named HTMLayout then). And Norton AV was market leader at that time.
Symantec did first security audit of Sciter source code.
You (AV vendor) have UI engine that fits most of UI requirements (lightweight, supports i18n by nature, flexible to screen resolution, HTML/CSS is well known in UI) and, which is most valuable, secure. So decision is quite obvious.
Yet, psychological aspect.
AV product must look modern at any time. User may not trust AV app that looks outdated - that rises suspicion that it is not adequate to recent threats - so it must look modern. Therefore ability to modernize UI by CSS without touching anything else (happens at least once per year) is the key requirement. UI systems/frameworks that use designs nailed down to pixel grids are too expensive on the long run in such circumstances.
AV/security specific reasons:
First serious customer was Symantec with their Norton Antivirus. Norton AV 2007 was their first version that used Sciter (named HTMLayout then). And Norton AV was market leader at that time.
Symantec did first security audit of Sciter source code.
You (AV vendor) have UI engine that fits most of UI requirements (lightweight, supports i18n by nature, flexible to screen resolution, HTML/CSS is well known in UI) and, which is most valuable, secure. So decision is quite obvious.
Yet, psychological aspect.
AV product must look modern at any time. User may not trust AV app that looks outdated - that rises suspicion that it is not adequate to recent threats - so it must look modern. Therefore ability to modernize UI by CSS without touching anything else (happens at least once per year) is the key requirement. UI systems/frameworks that use designs nailed down to pixel grids are too expensive on the long run in such circumstances.