In case when I set 'Allow Empty: NO' for the custom property (For example 'Note'), which I added (Administration -> Edit Custom Properties -> Test Case -> ).
This rule works not as I expect...
Each moment when I try to create folder in 'Test Cases' space the validation occur and all following operations are unreachable.
I thought that - Required* validation should trigger only on Test case filling stage in Grid.
And why this rule works for the Folder, which I'm creating in 'Test case'?