UI: Quality of life improvments for the jump dialog

UI: Quit the jump dialog on success

This behavior matches what other editor do, so it will help the user to control the app more easily.

UI: Set the "ok" button as default of the jump dialog

This allows the user to press "12+Enter" and directly go to the 12th byte instead of needing to use tab or the mouse. It once again matches what most editor do.