+++ This bug was initially created as a clone of Bug #838565 +++
Admin portal -> Edit VM -> Custom Properties
when I select one and then decide to not use it and click "-" button,
it won't disappear. The only way how can I get rid of it is to add
another custom field by "+" and remove the former and keep the newly
added instead (since it starts correctly with nothing preselected)
Tried in 3.1 as of 1.7.2012
Verified - si11 - in case that last VM option is left and user removes it it's removed and none of options is left in list - initial VM options look is restored.