ActiveViewTheme
Sets a new theme for a view when it gains input focus.
Usage
Simply create a new color scheme file that you would like to use for your active views. You will probably want to place this in Packages/User/. Then, in Packages/User/ActiveViewTheme.sublime-settings, create a settings file, specifying the theme to use on active views. The path should be relative to one above the packages directory, the same as color_scheme in the Preferencs.sublime-settings.
{
"active_theme": <your theme path here>
}