[sawce]

What?

Why would you want to open .amxx? .amxx is the compiled binary file.

If youre trying to edit the source edit the corresponding .sma file instead. If you dont have the .sma and cannot find one its not really practical to decompile plugins, although it is possible

If youre trying to load the plugin put it in amxmodx/configs/plugins.ini. Use a path relative to amxmodx/plugins

eg: if youre going to add "amxmodx/plugins/abc.amxx" then open plugins.ini, and make a new line that says "abc.amxx"