focus + scrolling nits

a few nits about how scrolling, selection, and focus interplay:

1. switching between view filters should not remove focus from the main grid view. currently, the focus shifts to the filter list.
2. scrolling among the filters is likely much less common than scrolling within grid view. but if it was a design choice to have the view switch, then perhaps allow for quick tabbing betweem filter list and grid view?
3. action of Home and End keys is odd. it changes to the top or bottom chunk of the grid view but doesnt change selection.
4. if (3) is deliberate, then perhaps Ctrl-Home and Ctrl-End for changing to top or bottom?
5. after Home or End, the arrow keys change behavior: rather than changing selection they cause the grid view to scroll.
6. Typically Shift-Up and Shift-Down are used for scrolling a view rather than scrolling selection within view. In any case, it's not clear what the Up/Down keys are supposed to do and the behavior is inconsistent.

No files or tests are named. Start by locating the filter-list and grid-view focus handling plus the keyboard handlers for Home, End, arrow, and Shift-arrow keys. The issue needs settled expected behavior for focus, scrolling, and selection before implementation can be considered done.