bring multi-notebook from gedit.
render thumbnails
add alpha for snapshot.
setup text view
allow tabs to freeze themselves when in a dragging a notebook.
draw overlays for drop location
draw whole area
dragging wip.
spacing cleanup
notebook: ref the tab so it doesn't fall below one.
multi: remove redundancy in checking if in a drag.
incremental debug work
playground
foo
hi
blah
blah
freeze/thaw tabs during drag.
draw targets.
draw wrk