PSPad unicode 5.0.0 (171) English

Macari:

Oh.. that not good. The intern file browser in pspad use externals? When I double click on a file in pspad I want open it in pspad, not start it with a external program. ;)

Not. But if you click on any file what has no assigned extension (e.g. picture), PSPad open it in default associated application.
If you want to open it in PSPad, visit highlighter settings and add extension SCSS to highlighter or use right mouse and select open in PSPad