Preferably popup, would be really nice to get a nice popup when my trees are done, so I don't have to keep opening the farming timer to check.
Can't imagine it would be too terribly hard to implement, I think one of the first things you learn in programming is a Hello World dialogue box (don't quote me on that)
But anyway this would be cool, especially if I come home and have a popup on my screen I know my trees are done.
I've looked into this before and it it a lot more complicated than that to do it the proper way.
The messagebox itself is indeed one line of code for an simple one. However there are a lot of edge cases in deciding when the messagebox should appear (restarting alt1, multiple trees, editing them etc.). The app would have to run before showing the message to make sure the timings still match, so i'd have to make a way to let apps run in the background. You see where this is going.
There are quick and dirty ways to do it. I could could make it show a popup after you minimize the app window, i'm not sure if that defeats the purpose of this idea.