The drag-and-drop is done from scratch. Quirk just listens to browser events like mousedown/mousemove/mouseup and turns that into manipulations of the circuit.

The drag-and-drop is done from scratch. Quirk just listens to browser events like mousedown/mousemove/mouseup and turns that into manipulations of the circuit. Getting it to work well across all the browsers, and modes of interactions, is quite finicky. For example, mobile browsers refused to not scroll even if `event.preventDefault()` was called, so I had to overlay the drag targets with transparent divs that have `touch-action: none`. Quirk doesn't have menus.. you might be thinking of the recording of Davy's simulator? Those menus also look custom-made. I actually wouldn't call them "nice", because they lack important polish. Read this: http://bjk5.com/post/44698559168/breaking-down-amazons-mega-dropdown http://bjk5.com/post/44698559168/breaking-down-amazons-mega-... I'm sure there are libraries for menus and things like that, but I generally prefer to try to do it myself unless those libraries have a really good interface.