webix.event declaration in webix.d.ts

[alexandrklimov]

Hello Webix team!

Current declaration of the webix.event function in the webix.d.ts file doesn't allow us to attach an eventhandler to a Window, coz window isn't HTMLElement.

May be I'm wrong somewhere?
Could you please fix this issue someway if I'm right.

P.S.: for now, I'm using the next workaround
(webix as any).event(...);