Create an inspector manager that allows inspector widgets to be closed and disposed without interrupting notebook and console ability to send inspection messages.

src/inspector/plugin.ts

@@ -22,30 +22,78 @@ import {
 export
 const inspectorProvider: JupyterLabPlugin<IInspector> = {
   id: 'jupyter.services.inspector',
-  provides: IInspector,
   requires: [ICommandPalette],
+  provides: IInspector,
   activate: activateInspector
 };
 
 
+/**
+ * A class that manages inspector widget instances and offers persistent
+ * `IInspector` instance that other plugins can communicate with.
+ */
+class InspectorManager implements IInspector {
+  /**
+   * The current inspector widget.
+   */
+  get inspector(): Inspector {
+    return this._inspector;
+  }
+  set inspector(inspector: Inspector) {
+    if (this._inspector === inspector) {
+      return;
+    }
+    this._inspector = inspector;
+  }
+
+  /**
+   * The source of events the inspector panel listens for.
+   */
+  get source(): Inspector.IInspectable {
+    if (this._inspector && !this._inspector.isDisposed) {
+      return this._inspector.source;
+    }
+    return null;
+  }
+  set source(source: Inspector.IInspectable) {
+    if (this._inspector && !this._inspector.isDisposed) {
+      this._inspector.source = source;
+    }
+  }
+
+  private _inspector: Inspector = null;
+}
+
+
 /**
  * Activate the console extension.
  */
 function activateInspector(app: JupyterLab, palette: ICommandPalette): IInspector {
-  let inspector = new Inspector({ items: Private.defaultInspectorItems });
+  let manager = new InspectorManager();
   let openInspectorCommand = 'inspector:open';
-  let opened = false;
 
-  inspector.id = 'jp-inspector';
-  inspector.title.label = 'Inspector';
-  inspector.title.closable = true;
+  function newInspector(): Inspector {
+    let inspector = new Inspector({ items: Private.defaultInspectorItems });
+    inspector.id = 'jp-inspector';
+    inspector.title.label = 'Inspector';
+    inspector.title.closable = true;
+    inspector.disposed.connect(() => {
+      if (manager.inspector === inspector) {
+        manager.inspector = null;
+      }
+    });
+    return inspector;
+  }
 
   function openInspector(): void {
-    if (!opened) {
-      app.shell.addToMainArea(inspector);
-      opened = true;
-    } else {
-      app.shell.activateMain(inspector.id);
+    if (!manager.inspector || manager.inspector.isDisposed) {
+      manager.inspector = newInspector();
+      app.shell.addToMainArea(manager.inspector);
+      return;
+    }
+    if (manager.inspector.isAttached) {
+      app.shell.activateMain(manager.inspector.id);
+      return;
     }
   }
 
@@ -59,7 +107,7 @@ function activateInspector(app: JupyterLab, palette: ICommandPalette): IInspecto
     category: 'Inspector'
   });
 
-  return inspector;
+  return manager;
 }
 
 /**