Octave does not close figures properly

[Fury kerry]

Hi,

When draw a lot of figures and close them (click the windows control- "x" button) , Octave does not end the corresponding "gnuplot" and "gnuplot_x11" process. As a result, after a series of drawing and close the figures, Octave end up with the following error:

Maximum number of clients reached 
gnuplot: unable to open display ':0'                                                                                                                                                
gnuplot: X11 aborted.                                                                                                                                                         I 

Command "ps aux | grep gnuplot" shows a lot of "gnuplot" and "gnuplot_x11" processes in interruptible sleep states ("S+")

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
fury      3769  0.0  0.0   6156  1560 pts/3    S+   10:18   0:00 gnuplot_x11
fury      3770  0.0  0.1  27964  6112 pts/3    S+   10:18   0:00 gnuplot
fury      3771  0.0  0.0   6156  1556 pts/3    S+   10:18   0:00 gnuplot_x11
fury      3772  0.0  0.1  27964  6148 pts/3    S+   10:19   0:00 gnuplot

...
...

My system configuration:
Octave 3.6.2
Ubuntu 12.10
KDE 4.9.3
gnuplot 4.6.0

Zhen 

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Zhen Zhang
Zhejiang University
Yuquan Campus
MSN:address@hidden