Previously, we would assign dock elements a minimum width/height of 2
pixels so that we could detect when the mouse approached the edge of a
hidden dock in order to show the chevron buttons. This, however, was
causing confusion for users, who expected that extra space to be
clickable in order to scroll editors located in the center dock.
With this commit we will instead register a global `mousemove` event on
the window right when attaching the workspace element to the DOM (the
event handler is debounced, so this shouldn't have any performance
consequence). Then, when mouse moves, we will programmatically detect
when it is approaching to the edge of a dock and show the chevron button
accordingly. This allows us to remove the `min-width` property from the
dock container element, which eliminates the confusing behavior
described above.
As a consequence of https://github.com/atom/atom/pull/15378, we are now
able to render highlight decorations in a separate div, as opposed to
having an highlight container for each tile.
Code-wise this is much simpler, because highlights spanning multiple
tiles can be represented via a single region and don't need to be split
across the tiles they span anymore. As a byproduct, performance should
improve as well, because the number of nodes that need to be managed
should decrease significantly.
This also fixes https://github.com/atom/atom/issues/15449, and other
similar rendering artifacts, because highlight decoration DOM nodes
won't need to move between tiles anymore when their position changes.
At the cost of a very minimal reduction in layout performance, we gain
reliable rendering at all line heights and don't have to worry about
characters that extend above/below the footprint of a line.
Signed-off-by: Nathan Sobo <nathan@github.com>
...because packages like `.git-diff` are relying on this behavior to
position their decorations. This didn't seem to degrade layout times, so
it makes sense to just add it to keep package breakage to a minimum.
Previously, the shadow boundary made this impossible, but the new CSS is
way simpler than the JS we’re replacing and removes another dependency
on DOM polling.
