When clicking on the `pageNumber` input, or when using the keyboard shortcut <kbd>Ctrl</kbd>+<kbd>Alt</kbd>+<kbd>G</kbd>, the element isn't just focused but its contents is actually *selected* so that the user doesn't need to clear the input before entering a new `pageNumber`.
However, the `GoToPage` named action is only using `focus`, so let's change this to be consistent.
The following document can be used for testing: http://www2.informatik.uni-freiburg.de/~frank/ENG/beamer/example/Beamer-class-example1.pdf#zoom=page-fit
[screeenshot]