Init button via XML: issue with events handling

Trying to init button via XML config.
Having an issue with adding event handler: event does not fire.
No errors in console. Looks like something is wrong on my side.

Tried both, “click” and “on”->“onItemClick”, according to manual.
https://snippet.webix.com/6lln90o2

I know, I’m doing something wrong, just don’t know what exactly.

Hello,

With simple button clicks you can provide a function in the native HTML onclick manner, i.e.: Code Snippet

Thanks for example.
What if I have more complex logic that does not fit in attribute?
How does the XML config should look like?