Ideally via an accessible variable, trends already have their own structs so adding unsigned 8 bit integer to select the trend in view and then a series of boolean variables or flags to screenshot, e.t.c. shouldn't be to difficult, a variable theme allowing people to choose a preset (current layout) or a custom which would essentially just be a cut out of the trend graph itself (no background, no buttons just a trend and an axis), this will allow us to use our own graphics. Let me know how you get on and if I can help you anymore, I hope it makes sense.