Can add Nodes to Monitor View

[martijnhabers]

Describe the bug
When in the Live Monitor tab, you can click on the background to add nodes just like in the editor view. Doesn't do much, but once a node is added it cant be moved and it will disappear as soon as a new tree is loaded in.

To Reproduce
Go to the monitor tab, monitor any BT, and double click the background to add a node.

Expected behavior
Nothing, shouldn't be possible to be edit trees in monitor tab

[facontidavide]

I will address this soon, thanks