When the SelectPage widget is opened from a table (reference table for example), the focus is lost and the value is not saved.

To fix this :

this.triggerDialogBoxOpened = true;

(in choosePage: function())

This have to be set back to false when the ChoosePage is closed, which will be done differently in 4.1 and 4.2

4.2 :

add the callback in _cancel with undefined

Check every calls to the callback to change the behaviour between null and undefined

Add documentation about null/undefined (null = selection removed, undefined = tool closed)

4.1 :

Add another callback that will be called by each function that close the box.

Add a deprecated comment to be sure that it is known that it is a 4.1 only fix