One-step Undo / redo of changes to current file

[saulgreenberg]

Add an undo function that undoes any changes to the currently displayed file (including markers). To do this: -save the data whenever we show a file -revert it on undo, while saving changed data so we can redo

Limitations:

• any changes to other records will disable undo e.g., with propagate, multiselections, etc.

[saulgreenberg]

2. Simple undo. Except for reverting to a previously saved database file, Timelapse has no undo facility. Unfortunately, it would be very difficult to add on at this point. However, I could implemented a limited undo at the image level that would work as follows. a. A user would navigate to that image – the data that is displayed is saved internally as a possible undo state. b. The user does some changes to the data, but then realizes that an error is made. c. When the user selects undo, Timelapse restore the data to what was captured in the ‘undo’ state i.e., what the data was when the user first navigated to that image. d. A redo would reverse the above e. Alternately, undo would restore the data field by field for that image (e.g., if the user changed ‘Temperature’ and then ‘Count’, the first undo would undo the changes to Count, and the second undo would undo the changes to ‘Temperature’.

Limitations: Undo is disabled if the user made changes that affects more than one image (e.g., by using ‘propagate’, or by entering data across multiple images using the new overview feature, or by any of the menu functions that affect multiple images)

[saulgreenberg]

Decided against this as having a one step undo doesn't add much value and can be confusing for non-undoable actions