Bug 1042319 - [Gallery] WIP patch of update gallery edit UI and visuals

It took me quite a while to understand what you were doing with this previousEdits object.  Maybe you could clarify the comment, or clarify the name of the variable to make it easier to understand.

Even better would be if you could integrate the previousEdits state with the editSettings state, so that the single editSettings object is enough to perform the edit and also enough to initialize the UI as needed.  The gamma and matrix settings are already duplicated between the two objects.  Consider adding properties like cropModeId and effectId to editSettings instead of maintaining this separate object.  (Unless that would add a lot more work to do it that way.)