If the zoom property is set on the body element for a preset zoom your window control does not seem to correctly take this zoom into account for the position and width/height of the window. You can easily recreate this in the following example application: https://stackblitz.com/edit/react-qmwfbf-fzmj98?file=app%2Fapp.tsx,index.html

Simply open the window using the button and then maximize the window in the title bar at the top. You can see that the width/height calculation is much too large and is not correctly maximized to the available space. You can also see this in the attached video.

A similar problem has already been reported here for popups https://github.com/telerik/kendo-react/issues/2320 and there is also a solution for this using the scale property in the PopupProps here:

<PopupPropsContext.Provider
      value={(props) => ({
        ...props,
        scale: 1.25,
      })}
    >

Please add exactly the same scale property for the WindowProps. 

Setting the stage prop to "DEFAULT" does not update the Window component as expected:

const [stage, setStage] = React.useState<string>('DEFAULT');  

const handleStageChange = (e: WindowActionsEvent) => {
    setStage('DEFAULT');
  };

<Window
          stage={stage}
          onStageChange={handleStageChange}

Setting the window position is not permanent.

How to reproduce:

1. open https://stackblitz.com/edit/react-hyhjxg?file=app%2Fapp.tsx
2. click 'move to corner' button
3. click the window title bar
4. the window changes its position to the previous one, but it should remain in place.

Chaging window stage also reverts previous position