@interact missing argument labels in JupyterLab

The sliders below should be labeled with x and y, the argument names.

from ipywidgets import interact, Output, HBox
left = Output()
right = Output()

with left:
    @interact(x=(0,10))
    def f(x):
        @interact(y=(0,x))
        def g(y):
            with right:
                print('Product',x*y)

print("Product calculator")                
HBox([left, right])

Edit: This only seems to be a problem in JupyterLab, not the notebook

[jasongrout]

Fixed in #889.

[jasongrout]

It appears that widgets inside a jupyterlab Output widget do not trigger the onAttached method, so the displayed promise never gets resolved. Here’s a simpler example that doesn’t work:

from IPython.display import display
from ipywidgets import Output, IntSlider
out = Output()

with out:
    display(IntSlider(description="hi"))
display(out)