[bug] pageup in deck builder

[Theo]

On Windows Chrome, the hitting the page up button when modifying a deck in the deck builder causes the pane with the deck portion boxes to move to the left and leave and empty pane on the right half. This means there is then no way to save or cancel the deck.

Workaround is to copy out the deck portions and refresh browser.

This does not happen on Windows Firefox, but it did seem to cause some weirdness after canceling out of the deck edit, where it got stuck 50/50 between the deck list view and the deck editing view, until I edited another deck.