There are two variants of adding a new element to your design:
To add a new element:
This way allows adding a new element by using the navigation buttons of Components tree.
To add a new element of the same nesting level as the currently selected one - click the button .
To add a new element of the lower nesting level to the currently selected one (to nest an element) - click .
There is the only way to delete an existing element. It consists in the following:
Select an element you wish to delete in the Components tree;
After clicking the button a confirm window will appear;
In the confirm window click OK to confirm the operation or Cancel to cancel it.