New nodes onto floating buffer

When writing notes, it would be useful to first enter the data and then (reprocess and) connect it to an existing structure.

Mudyc developed a nice solution demo for this.

1. press 'tab' to 'lost the focus'

2. enter the data and a new node is created

   Note: entering multi-line content should be allowed

3. press 'tab' to enter a new node

4. previously entered node remains non-connected and floats on view's nadir

Later the floating nodes can be connected to structure using mouse (keybindings should be possible, but mouse would be the most natural way).

In mudyc's demo connections were created in special mode with only mouse (using rmb_action_switch). Of course something like CTRL + mouse could also be considered.