It's interesting that the redraw rate seems to be a lot faster; I don't think I've changed anything related to that for awhile. It could be the newer version of Java being more efficient behind the scenes. Although it's possible that if you were several versions back, there may have been a change shortly after that one which I'm not recalling. I'm also glad the drop-down problem is solved - that is related to the newer version of Java.
I do agree with the rivers. I originally implemented it the way it was because I was frustrated with a lack of precision at times in Firaxis's editor when trying to get rivers to flow a particular way in a small area. But Firaxis's method is better for longer river placement. So I think having both options would be best. And I do have an idea on how to implement it - essentially it would use, instead of the current algorithm to determine which isometric tile was clicked on, a different one to determine which tile edge you are closest to. Perhaps with a "maximum distance from center" requirement so you don't wind up with rivers all over the place when clicking and moving from one tile to another.
I've also thought about adding a Firaxis-style "change surrounding tiles as necessary" paining option. I think Firaxis does it with a "if the surrounding tile isn't valid, change it to grassland if land; coast if sea" method, which may be the best way to go starting out.
I don't currently have Undo as it would require storing the previous state, which could include a number of affected tiles. It's possible, but not trivial, and it might be a good idea for me to research undo systems in general first. I added the auto-save functionality in part because it can partially alleviate this - it isn't as good as a robust Undo system, but does provide some measure of fallback.
There is a confirm-overwrite warning when saving to an existing filename, but I don't recall seeing two
. Then again, while I've tested functionality within the editor on OS X 10.9, I'm not sure I've tried
saving there, so your idea about the second warning being OS-related is possible.
There is an option in the Settings to confirm quitting (which should be on by default on a fresh download). It doesn't actually know whether there have been any changes and simply prompts on every exit, but it does prevent the situation of accidentally clicking the close icon and losing work.
Thanks again for the feedback - it's both useful to have someone else's real-use-case perspective on it (I've worked on the editor a lot more than on actual mods by this point), as well as encouraging that it is being used enough to have this good of feedback. I've been working on a different side project the past week or two for variety's sake, but will be getting back into it before too long.