select_item marker problem

Dear friends
                  I am using gtkextra to build a GUI. I have a dataset
and plot it using gtkplot. Now I want to select a data in the plot.
For that I used the signal

'select_item'

gtk_signal_connect(GTK_OBJECT(canvas), "select_item",  (GtkSignalFunc)
select_item, NULL);

now in this I don't want the marker in the plot. Please tell me how to stop it. 

Actually I use other gtkplot commands in the 'select_item' function, and use

gtk_plot_canvas_paint(GTK_PLOT_CANVAS(canvas));
gtk_plot_canvas_refresh(GTK_PLOT_CANVAS(canvas));

at the end.

Because of this the last point marker is also visible. That I don't want

Please suggest something

thanks is advance
Shamik


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