But for people downloading the version for windows with gtk included we should provide an workaround either in the help
Agreed. Either a [wiki entry](https://wiki.geany.org) or even better a pull request improving [the manual](https://www.geany.org/manual/current/index.html#defining-own-widget-styles-u...) would be much appreciated. I suspect most users don't fiddle with the GTK+ theme on Windows, so it hasn't been well documented yet.
So there is no analog with «...wanting a web browser's...» (unless the reference is for browsers that do not use window's theme but gtk's ) as codebrainz stated.
The analogy was to compare website CSS and browser window/widget themes to Scintilla editor widget themes and Geany window/widget themes. In the same way that CSS in a webpage doesn't control the appearance of the browser chrome/widgets, the Scintilla/editor area colour scheme in Geany doesn't affect the GTK+ theme. I stand by my apt analogy :smiley_cat: