This adds a new NodeModel, which can be passed from the TileLayout to
contained blocks. It contains all the layout data that the block should
care about, including focus status, whether a drag operation is
underway, whether the node is magnified, etc.
This also adds a focus stack for the layout, which will let the focus
switch to the last-focused node when the currently-focused one is
closed.
This also addresses a regression in the resize handles that caused them
to be offset from the cursor when dragged.
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Co-authored-by: sawka <mike.sawka@gmail.com>
This PR is a large refactoring of the layout code to move as much of the
layout state logic as possible into a unified model class, with atoms
and derived atoms to notify the display logic of changes. It also fixes
some latent bugs in the node resize code, significantly speeds up
response times for resizing and dragging, and sets us up to fully
replace the React-DnD library in the future.
