An item whose outline fits the printable area could still never be placed: the
arrange bed is inset by bed_shrink (1 mm per side) and the item is inflated by
its brim width, and the clamp meant to relax that only kicked in with more than
5 mm to spare. An item scaled to fit the print volume was therefore rejected
every time. Give the bed margin back where the largest selected item needs it,
never below the skirt distance, and cap the inflation at the printable area.
When an item comes back UNARRANGED, the GUI parked it on a virtual bed that was
never created, moving it a whole plate stride off the plate. Keep the instance
where it is instead, and when nothing could be placed at all, skip the plate
rebuild so a too large item cannot be re-homed to another plate.
Arrange no longer recycles plates: it must not delete a plate the user created,
even when the arrange leaves it empty.
Lam Wei Lun
4c85d0e80a