* Display property from linked object, colored green,
* Change DlgPropertyLink to support external linking and sub-object
selection
* Improve large selection performance by using a timer
* Improve TAB key behavior in property editor
* Add context menu to show hidden properties, change property status,
set expression on any and property, and add/remove dynamic properties
* Optimize expression completer model construction, as the original
implementation gets prohibitively slow for moderate number of objects.
