Can more than one treeviewnode in a tree be selected at once?

Ok, this is all you should need to set for multi-select listview.

SetWindowLong hWnd,-16,$40000000 or $10000000 or MYLBS

Where MYLBS is a combination of what you need below:

Const LBS_DISABLENOSCROLL=4096
Const LBS_EXTENDEDSEL=$800
Const LBS_HASSTRINGS=64
Const LBS_MULTICOLUMN=512
Const LBS_MULTIPLESEL=8
Const LBS_NODATA=$2000
Const LBS_NOINTEGRALHEIGHT=256
Const LBS_NOREDRAW=4
Const LBS_NOSEL=$4000
Const LBS_NOTIFY=1
Const LBS_OWNERDRAWFIXED=16
Const LBS_OWNERDRAWVARIABLE=32
Const LBS_SORT=2
Const LBS_STANDARD=$a00003
Const LBS_USETABSTOPS=128
Const LBS_WANTKEYBOARDINPUT=$400

$4000000= Child Window
$1000000= Visable

Hope this helps