In NX 11.0.1, when you click the X (Close) button on a part’s graphics window, the part will not close if it is used by another part that is also open in the NX session. If this is the case, the part’s window closes, but the part remains open. No confirmation message is displayed, as the part does not close. Also, as the part’s window closed, it is no longer considered “previously displayed” and so is not listed in the Window menu or by Switch Window (Ctrl+Tab).
Example: You open an assembly and change the displayed part to one of its component parts. You then click the X button on the graphics window. This will not close the component part, as it is used by the assembly that you opened. The benefit is that when you change the displayed part back to the assembly, the component is still open and displayed in context of the assembly.
If the part is not used by other parts in the NX session and you click the X button on the part’s graphics window, the part closes. In the above scenario, if you click the X button on the assembly part’s graphics window, the part will close. As before, a message will display asking if you want to close just the assembly part or both the part and its components. If you modified the part, a message will also display to ask if you want to save it.
Regardless if the part closes or not, when you click the X button, if the Change Displayed Part on Close customer default option is turned on, the previously displayed part will display. So this option continues to work as it always has.