One similar to the one in Adobe Photoshop would be nice (with a window that shows you all actions and you can go back an arbitrary number of actions at once). This feature should be optional, because it might be a memory hog. Also, there should be user setable parameters for how many undo levels to store, how much memory to take up, etc. A repeat option (ctrl+y) – like in Word - to repeat the last action would be nice as well.
GaryBader - 10/1/05 - this should be implemented as a public API with a consistent default GUI (probably an Adobe Illustrator like window that shows the undo stack). All core and plugin code would register with this API to handle their own undo/redo events. Until we have this, I think each plugin that wants to deal with undo/redo functionality should embed their UI elements that handle this e.g. undo/redo buttons within their own UI e.g. within a CytoPanel, and not in the menus to avoid user confusion that woud arise from only being able to undo the plugin actions and not being able to undo the majority of other actions in Cytoscape.