I can't reproduce #1 - It does have a selection mark in all platforms - though in WPF it is a very light grey since the control is not focussed..

from eto.

reviewed steps (WPF):
start testcase,
a)select [3]Name204, collapse collapse [2]Name20 item. press button. [3]Name202 Item is selected with usual mark!
b)collapse again [2]Name20 item. press button. [3]Name202 will be shown but without selection mark.
as for me this is bug because in (a) item is selected with usual mark,
in case item was already selected and after re-selecting it (or expanding parent), it loses usual mark

http://screencast.com/t/56dG6IdU5P

reviewed steps (mac):
collapse [2]Name20 item and expand it again. selection mark from [3]Name202 was disappeared

as a workaround for this I suggest (2) i.e. when selected item became invisible, (it's parent was collapsed), nearest visible parent should be set as selected

from eto.