Scoping

Since Module adds the Temporal attribute to your symbols, it is unclear when and how your dynamic symbols will be purged from the Kernel. Therefore, use LeakyModule to scope all dynamic symbols.

You can clean them up using ClearAll after a notebook has been closed or a cell has been destroyed. EventHandler methods are applicable to ResultCell, EvaluationNotebook, or even WindowObj.

info

Since WL 14.2 using LeakyModule is unnecessary. The native Module will do the job.