What impressed me most bug

　　Today met a bug, there is a small probability lead to incorrect tray restraint when plug usb interface, after I have been reproduced and view source code, and found that because the code is written in the original development of this logic is the default device connected , then I open in case the device is not connected software in connection usb lead to an adjustment backlight of the code logic is not turned on, when this piece of logic is not open state subsequent logic can not properly run lead to tray restraint incorrect, software case closed cycle of death and so on.