I noticed a strange behavior when trying to drag a node from the Node Repository onto a connection that is upstream of a node in paused or queued state:
If you try to drop a node onto the second connection here, it first seems to work and you get a dialog asking for confirmation:
After clicking OK however, nothing happens, which is a bit counter-intuitive.
Maybe the behavior can be improved, either by showing a more informative message in the dialog, or by disallowing the drop behavior in the first place, and showing an icon indicating that this action is forbidden at the current state.
Similarly, I’d suggest to disallow drag-and-drop when the dragged node has an incompatible set of input and output ports, as otherwise you can end up with a lot of lost connections that can be hard to rewire in complex workflows.
What do you think about these suggestions?