Any tips on debugging within event callbacks?

[deostroll]

For e.g.

def handle_click(x,y):
  print(x,y)

canvas.on_mouse_up(handle_click)

In this example print() doesn't show up...

[martinRenou]

Can you try capturing the print in an Output widget? As done in the documentation: https://ipycanvas.readthedocs.io/en/latest/events.html#built-in-mouse-events

Probably the documentation should be clearer as to why we're doing this.

Basically the JupyterLab front-end does not know under which cell it needs to put those prints (since it's in a callback, it does not go under a cell output). So it puts it in the JupyterLab logs panel, which is less discoverable. Capturing those prints and putting them in a cell output can be a way.