STEPS TO REPRODUCE (mouse)
1. reset combobox
2. click on the combobox
3. hover the options in the dropdown menu
4. click outside of popupmenu or press ESC key

selectedIndex should be -1.

(its value is logged in the textbox with 1 sec intervals)

STEPS TO REPRODUCE (keyboard)
1. reset combobox
2. click on the combobox
3. press UP/DOWN keys
4. press ESC key or click outside of popupmenu

Again, selectedIndex should be -1.