Log Message:
py-urwid: update to 2.6.9.

New features 🗹

    Support relative scroll for ListBox by @penguinolog in #858
    Absolute scrolling calculation is resource-hungry and can cause serious \ 
issues on the long lists.
    This change also rework calculation allowing to use ScrollBar with TreeList \ 
(users should prevent infinite load cycle on lazy-load self).

Bug fixes 🕷

    Support <shift> key reading for sgrmouse by @penguinolog in #859
    Historically key reading was not implemented due to \ 
<shift><click> for buttons 1-3 is handled by the most GUI terminal \ 
emulators itself.
    Fix regression in TreeWidget: original widget can be overridden by \ 
@penguinolog in #860