The Application layout » File tabs » Colors branch of Settings has the following options.
If selected the background color of file tabs will be based upon the file type. You can assign file types to the colors available in the table here by double-clicking on a color line and adding an extension (e.g. "*.html"). Additional extensions should be listed immediately following the preceding extension and a semicolon ";" (e.g. "*.php;*.php3;*.html;*.js"). If preferred, you can specify colors for individual files rather than extensions, e.g. "ResolveLine.cpp".
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