rose edit: stabilise Python 3 port #223
Description
(Placeholder issue to allow this to be included in Cylc project planning)
The Python 3 / GTK 3+ port of Rose Edit has been released, however, it is yet to be battle-hardened, it's currently at "beta" stability level with a number of known issues.
This is an umbrella issue to represent the ongoing effort to stabilise the new Rose Edit for general use.