The window stays open while the drawing is wired, so the table takes up
what the cables say on its own: each cable of the project is watched,
its change reloads the table after CableManager has worked the labels
out again, and a cable taken away empties the cells right away.
A reload never costs the user his own work: cell edits not applied yet
are kept, and a cell being typed in is left alone.
A cell worked out from a cable refuses to be written through setData(),
so the apply button, the paste and the deletion of texts leave it alone
too.
Three cases against fixtures/every_feature.qet (strip X1, wired
terminals, no cable): a wired terminal shows cable and core, the cells
go read only and nothing is written into the element; a core without a
colour is shown as its number; a value typed in by hand stays when no
cable is wired and comes back unchanged once the cable is gone.
Kellermorph