Hi, > Anyone else want to comment at this stage? As a user, would _you_ get > confused when you hit undo and all that changes is (eg) the layer > opacity? I would be very unhappy if changing the layer opacity from 100% to 50% would eat up a dozen or more undo-steps since each value_changed signal from the slider triggers an undo which causes another undo-step fall off the end of the undo queue. We could think about merging consecutive undo steps into one, but this wouldn't work well for paintstrokes for example. Another possibility would be to take only those undo-steps into account that save tiles. All other undo operations should consume so little memory that they can be safely ignored. Salut, Sven