Question: how to tell if canvas is connected?

[dsblank]

This may be a question for ipylab but it may require some low-level canvas API:

I'm trying to make some start-up code that will add a canvas in a panel using ipylab:

app = JupyterFrontEnd()

panel = None
for widget in app.shell.widgets.values():
    if hasattr(widget, "title") and widget.title.label == "TITLE":
        panel = widget
        break

if panel is None:
    panel = Panel()
    panel.children = [canvas]
    panel.title.label = "TITLE" 
    app.shell.add(panel, 'main', {'mode': 'split-right'})
else:
    panel.children = [canvas]

where canvas is my ipycanvas canvas.

The problem is that in JupyterLab, the panel is in the app.shell.widgets, but it is no longer "connected" in HTML dom language if the panel has been closed. Is there a way to get to the HTML canvas element "isConnected" via ipywidgets, or ipycanvas, even if the panel has been closed?

[martinRenou]

Adding @jtpio to this discussion who might know the answer 😊

[dsblank]

For now, it looks like ipylab objects persist. I'll ask over there. Thanks!

[jtpio]

Ah I forgot to reply here!

for widget in app.shell.widgets.values():

Normally app.shell.widgets is not part of the public API yet. Or you meant accessing the "private" _widgets property?

[dsblank]

No, it was app.shell.widgets but I'll ask some follow up questions over on ipylab.