Parent class of all Undo/Redo commands.
One command to handle many sub-commands, such as a multi-drag/drop etc.
Represents one GanttEvent delete action that can be undone/redone.
Represents one GanttEvent DND action that can be undone/redone.
Represents one resize event in the chart that can be done/redone.
Represents one GanttSection delete action that can be undone/redone.