Mousewheel zoom on the stage

[Frencil]

The IAEA Interactive Chart of Nuclides affords the user standard scroll-to-zoom/drag-to-move capabilities. The nuclides layout should do this too, probably by way of a clip path for the stage.

[Frencil]

The concept of layouts has given way to the concept of questions, but this is still a viable enhancement. To abstract it perhaps any given question could be "zoomable" with captions and specifics being defined with respect to a zoom level.