whether you work in layers (good) or not (bad IMHO) if you can copy the entire image to the clipboard then UVMapper Pro might be an ideal solution. UVM Pro can constantly display a 3D model with the clipboard as the texture - and since some graphics programs have "copy merged" kys and/or macro/script abilities, it should be a simple job to tap that key/sequence to get an updated view without having to save the bitmap. Having said which, UVM isn't free - just good value :)