Very nice..
Is this using some kind of skin?
This not a packaged skin. In Opus-speak, this is a single lister with a single tab on the Opus version of This PC with a custom vertical toolbar on the left and a custom horizontal toolbar on the top with no status bar on the bottom.. These are all independent GUI settings in Opus.
how did you place this buttons to title bar???
Seems like some system-wide monitor manager to me. I wouldn't know which exactly, but ones like Actual Window Manager and DisplayFusion do add such buttons to application windows for easy resizing/moving/docking/snapping.
Sorry, it wasn't my intention to promote another product on this website. I used display fusion to add those buttons to the titlebar for moving the window to other monitors easily.
Also directory opus let's you easily add a background image to various ui elements.