Bug 147687 Assert err happened with design ui
Run BIRT in workbench with argument -ea. Assert err happened when using design ui to open a design file.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/command/WrapperCommandStack.java
.getCommandStack( ) );
	}
	public WrapperCommandStack(
			org.eclipse.birt.report.model.api.CommandStack ar )
	{
		this.ar = ar;
	}
	public boolean canUndo( )
	{
		return ar.canUndo( );
	}
	public boolean canRedo( )
	{
		return ar.canRedo( );
	}
	public void undo( )
	{
		if ( canUndo( ) )
			ar.undo( );
	}
	public void redo( )
	{
		if ( canRedo( ) )
			ar.redo( );
	}
	public void flush( )
	{
		ar.flush( );
	}
	public Command getRedoCommand( )