Thanks for promising of adding "dirty flag".
To be clear, I will try to specify with separate paragraphs.
1) what you doing
I have around 100 animations in 100 separate Spine files which are in 100 separate folders. Like "animation1", "animation2" ... "animation100". I export these 100 animations in such way when export files of animation1 are in animation1 folder, export files of animation2 are in animation2 folder etc. Then I go to Unity and integrate them into the game from these folders.
2) what you actually see
I export animation1 to animation1 folder. Then I open animation2, press export and Spine exports it in the previous folder (animation1) by default which overwrites animation1 files. Every time I must choose the correct folder.
3) what you expected to see
I export animation1 to animation1 folder. Then I open animation2, press export and Spine exports animation2 in the animation2 folder etc.
According to your words that Spine has always remembered the last export folder, I don't know how it's possible but I hadn't this issue before 3.5.15
4) what you suggest to fix it.
I inquire to add the flag "export to the source file folder" which will export files into the folder where the opened Spine files is.
I hope my explanation is better this time. Sorry, maybe my English is not perfect.
Thanks! You're making the very good software.