list-gadget: cap max-width to min-width=width
list-gadget: cap max-width to min-width=width

since list-pane have scrolling pane, it may grow however it wants, so when we
remove elements, having max-width is fine because sheet it is drawn on has at
that moment of time bigger sieze. Fixes #414.

slyrus/mcclim,slyrus/mcclim