Hi, I am using Raspberry Pi 2. It could work properly, but it suddenly changed: The common mouse arrow becomes a cross "X". And I can only open one window at one time, the window cannot be minimize or maximize or move around. It even does not have
" close" button at the right top side of the window. I can only click "File" >>"Close the window". The detail picture is attached below. Does anyone know how to solve this ? Thank you in advance.