My breakout program is getting near completion. I found the following problem, though. After hitting the bottom, I'm erasing the old ball, placing a new ball in the same manner as in the starting routine, then wait for the click as shown below.
The new ball does appear at the center of the window, but it stays there even I click (or right click) the mouse. The paddle does not move, either. So it looks like the whole program gets frozen. My GDB analysis shows the program resumes the subsequent steps and eventually reaches ball moving steps. Then why the ball does not move?! If anyone can give me suggestions, I would very much appreciate it... Thank you in advance!