Bug 141959 Changing data set didn't clean old column bindings
Steps to reproduce: 1.Add two data sets, "ds1" and "ds2" 2.Add a table, binding with "ds1". All "ds1" column bindings generate automatically, that's good 3.Change "ds1" to None Expected result: All "ds1" column bindings should be cleaned Actual result: All "ds1" column bindings are still there. If changing to "ds2", "ds2" column bindings will be added after them.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ColumnBindingDialog.java
getOkButton( ).setEnabled( okEnable );
	}
	private ComputedColumnHandle getSelectColumnHandle( )
	{
		if ( selectedColumnName != null )
		{
			for ( int i = 0; i < bindingTable.getTable( ).getItemCount( ) - 1; i++ )
			{
				ComputedColumnHandle handle = (ComputedColumnHandle) bindingTable.getElementAt( i );
				if ( selectedColumnName.equals( handle.getName( ) ) )
				{
					return handle;
				}
			}
		}
		return null;
	}
	private void updateSelection( )
	{
		if ( canSelect )
		{
			( (CheckboxTableViewer) bindingTable ).setAllChecked( false );
			( (CheckboxTableViewer) bindingTable ).setGrayed( dummyChoice, true );
			if ( getSelectColumnHandle( ) != null )
			{
				( (CheckboxTableViewer) bindingTable ).setChecked( getSelectColumnHandle( ),
						true );
			}
		}
	}