Second click doesn't work when mouse is out of the image boundary 

When the mouse is out of the image boundary , the second click doesn't work, I have to move the mouse back and forth to see the "+" mark and click to complete the label. 
Maybe I'm asking too much. But getting the mouse right at the edge is really annoying. The purpose of this tool is to save some time, right?
I could just drag the mouse out of the image while using labelImg. 