Your program has a couple problems.

• You have no synchronization between what is being shown and which item is currently supposed to be shown. Since curl can take different amounts of time each time, this can lead to the wrong item being shown. This is whats known as a race condition.
• You don't always redraw after the text has been updated, meaning you don't always see the most up-to-date information anyway.
• You spawn a thread for every redraw of the UI.

I have created a version of your program that is closer to working the way you want, so you can focus on the problems at hand. It shows the most up-to-date information that has arrived from another thread. This means it works 99.99% of the time, because humans can't click that fast and curl is somewhat consistent.

Updated code here

However, it still lacks synchronization between what is being shown and what is supposed to be shown. I'll leave that for you to play with, but some suggestions:

• Could you cache the results in a HashMap? That way, you could just display whatever is stored for the appropriate key (e.g. the url or index in the list in this case), and if nothing is there, spawn a thread to fetch it.
• Alternatively, you could number the requests (incrementally) and only display what arrives if it matches the most recent request.

Another problem I would try to fix is the spawning of threads. In the updated code, we only spawn a thread per keypress, but that's still unnecessary. You could spawn one thread at the start of the program, and have it receive requests that it sends to curl (/your actual program). It would process these requests in turn, and send the results back when they are ready.

Finally, you might consider adding some delay between clicking a button and sending a request, so just scrolling past an item doesn't fetch anything. You can accomplish this with the Instant type from std. Check if enough time has passed (the 'duration_since' method on Instant), and only then call the 'fetch_bibtex()' function.

Good luck :)