Go to root directory when changing directory handle

This is needed if we switch from one directory handle to another,
otherwise the old path from the old directory handle is kept and invalid

Author: martinRenou

src/index.ts

@@ -52,10 +52,13 @@ const plugin: JupyterFrontEndPlugin<void> = {
     const openDirectoryButton = new ToolbarButton({
       icon: folderIcon,
       onClick: async () => {
-        const fileHandle = await window.showDirectoryPicker();
+        const directoryHandle = await window.showDirectoryPicker();
 
-        if (fileHandle) {
-          drive.rootHandle = fileHandle;
+        if (directoryHandle) {
+          drive.rootHandle = directoryHandle;
+
+          // Go to root directory
+          widget.model.cd('/');
         }
       },
       tooltip: trans.__('Open a new folder')