Easily done. Open your www/ui2 folder and create a text file named exactly ui2-local-overrides.css
Open this file in notepad or whatever and paste in:
Code:.cliptile.selected { background-color: rgba(0,255,0,0.4); }
UI2 is coded to load that file if it exists. That will turn the selected clip a medium shade of green. You can put any valid CSS color value there instead of rgba(0,255,0,0.4). For example #660000 for a dark red or Purple for purple. The best part is, because I don't include a ui2-local-overrides.css file in the distribution, it won't be replaced when you update so your change should survive for the foreseeable future.
You can, in Blue Iris, and it will also affect UI2. That is the only way to do it.
Worked great - thanks