associate a workflow with "Folder" in vSphere Web Client Integration

I'd like to call a workflow whose argument type is "VC:VmFolder" from context menu of some folder.

But invoked workflow isn't set its argument.

Are there any tips or workaround ?

1. select a workflow [Delete lab] on context menu of the folder [5.5.0b] (picture: 1.png)
2. popup dialog shows a workflow argument whose type is VC:VmFolder is not set automatically. (picture: 2.png)
3. select some folder for the argument [targetFolder] (picture: 3.png)

Thanks,

-Mitz