[news.eclipse.platform.swt] Is there a way to stop changing thumb positi

[spring_lcl@xxxxxxxxxxx (Chun Ling Li)]

Now I am drawing something on Canvas. But I met some ScrollBar problems of 
SWT.
When I click the scrollbar to display the figures of next page on Canvas, 
my application will fetch the data from network. What I want is to stop 
the thumb changing its position when fetching data. Only after my 
application has finished fetching the data from network, the thumb can 
move to the right position.
Can ScrollBar of SWT has such function to support such behavior?