This is similar to spider solitaire, because it was inspired by it :)
I used to play spider daily but found the vanilla version too easy. So to make it more difficult I would at the beginning of a new game deal the leftover cards until there were only enough for 2 more rounds and I always thought the fun began when I had 1 free slot on the table. After years of this I started wishing I could just start with the setting where all cards are dealt and I have free slots on the table.
So that is the origin story of this game.
And thanks for the bug report. I don't currently have any plans on updating this, but if I do I'll try to fix it.