I wrote that after a U disk was pulled out, a pop-up window said that the U disk had been pulled out. As follows:

        var windowView;
        windowView = View.window {
            type: View.POPUP_WINDOW,
            url: self.url("./pop_usb.html"),
            alignment: 3,
            // 
            parameters: { 
                data: {
                    name: "1",
                    drive: "2"
                }
            },
            screen: 0
        };

        // delaysetTimeout
        delay(1500, function () {
            windowView.close();
        });

found that the pop-up window could not come out, and then changed the delay from 1500 to 10,000, so that it could come out. I summed up and felt that the pop-up window came out so late that it was dropped by close before it came out 1.5 seconds later, and sometimes it didn"t come out even after 10 seconds. But when I touch the main window manually, I can come out right away. This is an amazing thing. I never figured out why the pop-up window sometimes didn"t come out, or came out late.