Pin windows on top, control their transparency, and jump straight to the file behind them.
Press Ctrl+Win+Alt+P to pin or unpin the current window so it stays on top of others. You can also do this from the window's system menu (right-click its title bar, or press Alt+Space).
Press Ctrl+Win+Alt+S, or choose Opacity... from the window's system menu, to open an opacity dialog for the current window. Window+ remembers your transparency and pin settings per application, so they're restored the next time you open it.
Press Ctrl+Win+Alt+E, or use the system menu's File submenu, to show the file the active window has open in File Explorer. From the same submenu you can comment on that file or copy a link to it directly to your clipboard.
Open Settings to set pin or opacity rules for specific applications or window titles, or to exclude certain applications from Window+ entirely.