My default Geany installation on Debian does not recognize some file types out of the box. How can I add extensions, using the same syntax highlighting as other known extensions for simplicity's sake?
In the current case, I'd like Geany to open all .aspx files with the same highlighting as .html files.
Use inside the menu Tools->Configuration files->filetype_extensions.conf. This will allow you to configure the filetypes based on suffix for your user.