Buggy ObjectField and object picking in general

Bug:

There is a bug in ObjectField:

• pick one object in it but None, close it
• start picking another object but press Esc
• the operation should be canceled but in fact None is returned !

Pressing Esc is supposed to cancel the picking operation instead of returning a null object.

Feature:

The other thing related to object picking is ObjectSelector, I believe it should be made public since it's very convenient to use when you want to show an object picker from code. Sadly, the list of allowed IDs is not implemented, that would have allowed to filter out the list of presented objects.

PS I have been able to fix the aforementioned bug by directly implementing my own object field UIElement which would in turn invoke ObjectSelector, which in turn would only update the binding-path when the picked object is not null (OnClosed parameter). TL;DR; boring but effective fix to the bug in ObjectField.

Thanks !

bug report: https://fogbugz.unity3d.com/default.asp?1123688_nlhoeqqq161dfc2k