scenario: use keyboard to position viewport so that top of cursor pane is above viewport start editing

Before this commit the cursor would stay outside the viewport (usually at 1,1 by default) As a result it would not receive any keys.

This is fine if we scroll off the viewport after turning on edit. It's kinda nice not to move the cursor unless requested. However, it feels weird as an initial condition right when a pane is starting to be edited. In that situation it isn't surprising to move the cursor.