Load external savefiles into mGBA 1-4 save slots

[Berbe]

Version: 0.10.3 This is related to #1072.

Here is the steps I followed:

1. File > Load ROM… <- Loaded game ROM
2. File > Save games > Use player 1 save game
3. File > Save games > Load alternate save game… <- Loaded external .sav file
4. Continued the game and used the in-game save feature
5. Restarted mGBA: player 1 save game still selected No save game loaded

I also tried:

• another slot
• the Load temporary save game… option

to no avail

What am I doing wrong?