Currently, there is no setting to control this.    In X9 and prior, if you opened a plan view from layout and you already had a plan view open, the program would automatically change all of the view settings to match what was sent to layout.  In X10, if no open view matches the layout, we automatically open up a new view.  This was done because we felt that changing the settings in an already open view was not a good thing to do.  In X9, the program encouraged you to work in a single p