Topmost -[true,false] The default is false, but if set to true, your Window will stay on top of other windows unless minimized. Only useful for special situations.
WindowState[Maximized,Minimized,Normal] - Controls the initial window state. It can be either Normal, Maximized or Minimized. The default is Normal, which is what you should use unless you want your window to start either maximized or minimized.
ResizeMode - [CanMinimize,CanResize,CanResizeWithGrip,NoResize]This controls whether and how the end-user can resize your window. The default is CanResize, which allows the user to resize the window like any other window, either by using the maximize/minimize buttons or by dragging one of the edges. CanMinimize will allow the user to minimize the window, but not to maximize it or drag it bigger or smaller. NoResize is the strictest one, where the maximize and minimize buttons are removed and the window can't be dragged bigger or smaller.