How to connect nodes very fast using shortcut? In Compositing nodes window there is an option to quickly connect the selected node to a viewer node using some kind of keyboard shortcut. I can't remember what it was. The only thing I remember is, that you have to hover the cursor over the active node's output (as shown below), press RMB or LMB and some kind of shortcut. Thanks for help in advance.


One other thing is interesting to me. When I hover the cursor over the selected node's output and press SHIFT+Right-click it become highlighted. What is this kind of selection for?
Ctrl+Shift+Left-Click on the node and it will connect to the viewer node. If no viewer exists, it will create one.

You can also select two different nodes and press F to connect them automatically (they will try and connect from the first output to the first input if they are available).

The Shift+Left-Click (or right-click as you mentioned) on the node socket output allows you to select which specific node sockets are connected when using F. This means you can also Shift+Left-Click on the target node socket to select which input it will connect to (by default it will connect to the next free input on the node).