check for windowing mode and turn it off if set to 'full' with a warn…

…ing in console

README.md

@@ -15,15 +15,22 @@ It was preferred not to re-use the term 'split', because in jupyterlab _split_ a
 
 Starting with jlab 4.2, the `windowingMode` setting in the `notebook` extension defaults to `full`  
 This setting enables [an optimized display algorithm](https://jupyterlab.readthedocs.io/en/stable/developer/performance.html#windowed-list), that currently **is incompatible with the `gridwidth`** extension  
-So as a short-term workaround, for using this extension, you can set this back to `none` in the `Settings Editor`, like so
+So as a short-term workaround, for using this extension, you can set this back to `none` in the `Settings Editor`, see the illustration below
+
+```{admonition} Important Note
+:class: warning
+
+Starting with 0.4.0, the extension will **silently change this setting for you**  
+Next releases will likely include a more user-friendly way to handle this
+```
+
+[see also this issue for more details](https://github.com/parmentelat/jupyterlab-gridwidth/issues/16)
 
 ```{image} README-windowing-mode.png
 :align: center
 :width: 600px
 ```
 
-[see also this issue for more details](https://github.com/parmentelat/jupyterlab-gridwidth/issues/16)
-
 ```python
 
 ## Requirements

src/index.ts

@@ -47,6 +47,22 @@ const plugin: JupyterFrontEndPlugin<void> = {
   ) => {
     console.log('extension jupyterlab-gridwidth is activating')
 
+    // force notebook windowing-mode to 'none'
+    // unconditionally for now, will soon provide a less autocratic approach
+    settingRegistry.load('@jupyterlab/notebook-extension:tracker').then(
+      (nbSettings: ISettingRegistry.ISettings) => {
+        const former = nbSettings.get('windowingMode').composite as string
+        if (former === 'full') {
+          nbSettings.set('windowingMode', 'none'),
+          console.warn('jupyterlab-gridwidth: windowing mode TURNED OFF')
+        } else {
+          console.log(`jupyterlab-gridwidth: windowing mode already ${former} - unchanged`)
+        }
+      },
+      (err: Error) =>
+          console.error(`jupyterlab-gridwidth: Could not turn off windowing mode: ${err}`)
+    )
+
     let command
 
     // gridwidth-1-2..gridwidth-1-6