How can i undo in the Designer Viewer?

How can i undo in the Designer Viewer ?
I do not see this option anywhere and the right mouse click does not work

While working to a project there is an undo option in block section only. In Designer View there is no such option and keep in mind that when you delete a component from designer view assorted blocks will also be deleted. Once your project is saved there is no option for undo. So keep regular backups of your projects to your computer - Project->Export .aia file facility and also you can use Project->SaveAs for versioning.