The control flows the following way:
- we receive SDL_KEYDOWN with letter 's' in the adventure map interface
- save dialog opens
- text input receives focus
- text input enables receiving SDL_KeyboardEvent-s which go between DOWN and UP
- the button on keyboard becomes UP (the menu opens very fast)
- text input receives SDL_KeyboardEvent and inserts 's'
- text input receives SDL_KEYUP
So the apparent fix is to open the save dialog on SDL_KEYUP event