Treeview rendering slowness

[z2274394 student unsw edu au]

Hello all,

I am new to GTK. I got a GtkTreeView(list) with 15 columns and 16000 rows
storing doubles. It is very slow at startup but at least it works. It uses
multiple selection and when user selects rows, it runs a callback function. The
callback function runs a for loop on all rows selected and is quite slow when
more than 1000 rows are highlighted. The problem is not the slowness of the
callback, but the treeview widget doesnt render itself with the selection
proberly. ie, pressing ctrl-A and have to wait 10 sec to see that it is all
highlighted. I think the treeview widget redraws itself after finishing the
callback.

Is there a way to do the drawing first (ie show what the user have selected)
then run the callback function in the background, with preferably a progress bar
etc.

Thanks in advance 
Johnson