Kickoff: optionally place sidebar on the right

Always placing the category sidebar on the left made it an obstacle to reaching the favorites when Kickoff was located at the left edge of the screen. The direct path to select an item from the Favorites list required the user to move the mouse across the sidebar area, and if the journey across sidebar items took longer than half a second or curved/veered in a way that the triangle filter doesn't expect, it would be interpreted as a hovering sidebar selection, removing the favorites from view and disorienting the user. Since humans don't always move mice in quick, perfectly linear motions, this frustrated more than a few people rather often.

It was especially problematic when Kickoff was at the bottom left corner of the screen, because the sidebar's Favorites category item (which is always at the top of the list) was then as far away from the mouse as possible, adding insult to injury by making it extra inconvenient to find and click whenever the user had to restore the favorites to view.

Then, after restoring the favorites to view, the original experience could easily repeat as the user once again moved the mouse from the sidebar's Favorites category item, across the sidebar, toward their target in the Favorites list.

Solution:

This patch adds a config option to place the sidebar on the right, so people can have their favorites near the mouse when it opens.

Layout mirroring is respected, so Tab key navigation should work just as well in locales with right-to-left Tab key navigation as it does with left-to-right.

BUG: 443082 FIXED-IN: 6.0