Call once and mount the result on every page through BoxTransformLayer, so one gesture cannot
be split across two page instances.
Precedence against drawing lives one level up: DrawFieldLayer covers the whole page at
z-index: 4 while armed, above this layer's z-index: 3, so a drag begun while the user is
drawing draws — every other drag on a box moves it.
Call once and mount the result on every page through
BoxTransformLayer, so one gesture cannot be split across two page instances.Precedence against drawing lives one level up:
DrawFieldLayercovers the whole page atz-index: 4while armed, above this layer'sz-index: 3, so a drag begun while the user is drawing draws — every other drag on a box moves it.