Set position for new window

hello i open a new window with:

<a 开发者_Go百科href ="javascript:NewWindow =window.open('Default.aspx', 'NewWindow' , 'width=400, height=450'); NewWindow.focus()">Hilfe</a>

at the moment the new window appears in the upper left corner. how can i set the position, so it appears somewhere else?

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By providing top and left:

window.open('Default.aspx', 'NewWindow' , 'top=100, left=100, width=400, height=450')