How can i use vscode webview in the Theia extension?

Hello friends, i want to open a webview pannel in the Theia extension, so i import vscode, but when i call vscode.window.createWebviewPanel, it says createWebviewPanel unsupported, i donot know why?

The extension code is as below

[original thread by PeimingMo]

Which version of Theia? Could you share GitHub repo with your extension?