a long time ago we used minimum/maximum window sizes
for the minimum and maximum length of the panel, but now this
is not necessary anymore as they are stored separatedly.

setting minimum then maximum then resizing can sometimes cause
several subsequent resize attempts, and a wrong order of setminimum/setMaximum
can even fail the resize completely

The size is saved as a private member as source of truth: when we reposition the panel
we can have not yet received a configure event of the last size we called resize()
upon, making that former resize fail

BUG:477317