Missing `leafmap` Widget Slider in Positron Notebook Editor

Description

In Positron Notebook Editor, leafmap renders maps correctly but fails to display overlay widgets such as an opacity slider added via ipywidgets. The widget is not rendered in the map UI despite being correctly attached to the map object.

Steps to Reproduce

1. Install dependencies:

%pip install leafmap

2. Run the following code:

import leafmap
import ipywidgets as widgets

m = leafmap.Map()

slider = widgets.IntSlider(
    description='Opacity',
    min=0,
    max=100,
    value=50
)

m.add_widget(slider, position='bottomright')

m

Observed Behavior

• Map renders successfully in Positron Notebook Editor
• No opacity slider widget appears in the UI
• The bottom-right overlay region is empty

Expected Behavior

• The ipywidgets.IntSlider should appear as an overlay control on the map
• Slider should be visible in the bottom-right corner
• Widget should be interactive and synchronized with kernel state
• Behavior should match JupyterLab rendering

Comparison

JupyterLab:

• Widget renders correctly
• Opacity slider appears in bottom-right overlay
• Fully interactive

Positron Notebook Editor:

• Map renders
• Widget does not appear
• Overlay control system appears non-functional or incomplete

Impact

• Loss of interactive map controls
• Reduced parity with JupyterLab notebook experience
• Breaks workflows relying on leafmap + ipywidgets integration

Notes / Possible Cause

IMPORTANT: ipywidgets remain functional as part of output cells by themselves. Issue here is different fromm previously reported ones.

Likely related to incomplete support for:

• ipywidgets rendering in notebook output cells
• ipyleaflet overlay widget mounting system
• DOM integration layer for map overlays in Positron
• Widget state synchronization between kernel and frontend

Missing overlaying widget slider (Opacity) from leafmap map

Positron Notebook Editor

vs. Desired Behavior (notice Opacity widget slider on lower right).

Originally posted by @rodrigosf672 in #11802

---

Positron Version: 2026.05.0 build 30
Code - OSS Version: 1.109.2
Commit: d2bce05424152f00e9164e2ea655d53d32e6e232
Date: 2026-04-09T07:51:26.722Z
Electron: 39.3.0
Chromium: 142.0.7444.265
Node.js: 22.21.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 25.3.0

Start by reproducing the leafmap and ipywidgets example in the Positron Notebook Editor, then compare its output with JupyterLab. Trace notebook output widget mounting, the ipyleaflet overlay integration, and widget state synchronization; done means the slider appears in the map’s bottom-right corner and remains interactive with kernel state.