KfW GUI -- update expand/collapse icon rendering

Use DrawThemeBackground() to draw the icons from the explorer treeview.

(cherry picked from commit 28d8e44e3474afcc1ea3b472c3336bd1017b55a6)

https://github.com/krb5/krb5/commit/6c3e07f32ca832479185b66c9f889d6dde844c6a
Author: Kevin Wasserman <kevin.wasserman@painless-security.com>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 6c3e07f32ca832479185b66c9f889d6dde844c6a
Branch: krb5-1.10
 src/windows/leash/LeashView.cpp |   33 +++++++++++++++++++++++----------
 1 files changed, 23 insertions(+), 10 deletions(-)