On start TuxPaint opens the last saved image, but when trying to open other saved images it doesn't seem to find it

This is due to differences in dirent structures. TuxPaint sorts an array of structures in memory for files to open.
As a result, the d_name field is lost during sorting.
Left structure in linux, right in haiku.
I try to fix it for haiku.
ta-da!
It's works

Thanks @threedeyes ! I'll try to see if we could get this change up streamed for future release :)
Thanks!