If you copy the blob of text starting with "%%WGT0" and ending in the final "}" to your operating system's clipboard, and then within Decker choose "Edit -> Paste Widgets" (or "Edit -> Paste" in web-decker), the sample contraption instance along with its prototype will be added to the current card. If you already have a prototype with an identical name and a lower "version" number, the revised prototype will upgrade any existing contraption in place.
The "%%WGT0{...}" format is literally how widgets (and their dependencies; referenced fonts and prototypes) are represented in the system clipboard by Decker.