Bug 206489 [Markers] Tasks column too small in the new markers view
Tasks column too small in the new markers view. We need to take into account the twistie.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/ExtendedMarkersView.java
viewer.setUseHashlookup(true);
		createColumns(new TreeColumn[0]);
		viewer.setContentProvider(getContentProvider(viewer));
		viewer.getTree().setItemCount(builder.getElements().length);
		viewer.setInput(builder);
		if (memento != null) {
			Scrollable scrollable = (Scrollable) viewer.getControl();
			ScrollBar bar = scrollable.getVerticalBar();
			if (bar != null) {
				Integer position = memento.getInteger(TAG_VERTICAL_POSITION);
				if (position != null)
					bar.setSelection(position.intValue());
			}
			bar = scrollable.getHorizontalBar();
			if (bar != null) {
				Integer position = memento.getInteger(TAG_HORIZONTAL_POSITION);
				if (position != null)
					bar.setSelection(position.intValue());
			}
		}
		getSite().setSelectionProvider(viewer);
		
		ISelectionListener listener = getPageSelectionListener();
		getSite().getPage().addSelectionListener(listener);
		listener.selectionChanged(getSite().getPage().getActivePart(),
				getSite().getPage().getSelection());
		viewer.addOpenListener(new IOpenListener() {
			public void open(OpenEvent event) {
				openSelectedMarkers();
			}