Document function ( ) { return document ; }
gets the document this performer is working on.may be null for an app-wide command performer . concode_field_sep CommandHistory history concode_elem_sep Document document concode_elem_sep List<CommandListener> listeners concode_field_sep void undoMultipleSteps concode_elem_sep void undo concode_elem_sep void removeCommandListener concode_elem_sep void addCommandListener concode_elem_sep boolean isUndoPossible concode_elem_sep void redo concode_elem_sep void execute concode_elem_sep boolean isRedoPossible