@Override
            public void widgetSelected(SelectionEvent event) {
                scrollVertically((ScrollBar) event.widget);
            }
Constructor for ScrollableCanvas.

@param parent the parent of this control.
@param style  the style of this control.
plugins/org.jkiss.dbeaver.ui.editors.image/src/org/jkiss/dbeaver/ui/controls/imageview/ImageViewCanvas.java