for all the usual reasons why composition is better than inheritance,
but in particular because I want to have a listbox that has a scrollbar
but not our custom tab behaviour in another branch. decoration in urwid
is not as transparent as it sometimes seems it should be but luckily
there's only one view that does much with its listbox and it was due
for some cleanup anyway.
read title and footer from the view instance, make views respsonsible for rendering
the excerpt
adapts infrastructure, welcome, keyboard, network views
Before this change, subiquity has lots of ListBoxes that just contain a single
Pile containing all their contents. This is (a) a bit silly (b) make some parts
of the scrolling experience a bit poor, for example urwid tries to scroll all
of a ListBox element into view when it gets focus but this is defeated by
shoving all the elements into a Pile (this causes
https://bugs.launchpad.net/subiquity/+bug/1750058 and a few other strange
bits).
The fix for this is obvious (don't wrap ListBox elements in a Pile) but this
breaks some aspects of tab cycling (when you shift tab back into a listbox you
want the last element of the box to be both selected and scrolled into view,
that sort of thing). Fixing all these bits of broken behaviour required
rewriting the tab cycling implementation to the point of copy/paste/hack-ing
the Pile.keypress method. Rather than doing the same for Columns, I just
prevent the creation of Columns with more than 1 selectable, which as we want
subiquity to be navigable with up/down/return does not seem so bad.
As penitence for all this, I've added a bunch of commentary explaining what is
going on.
This is the only place in subiquity today where we have selectable fields side
by side, which contradicts the goal to be able to navigate subiquity with up,
down and enter keys only. Replace the existing fancy widget with two fields,
one to select the import source and one to enter the username.
Also remove the "Ubuntu SSO" option as that has never worked.
before this, if you press up on e.g. the network view, focus would go to the first nic
not the last as you might expect. this is pretty obscure but oh well. such is urwid.
Michael Hudson-Doyle