Unofficial wii build -test-

[askot]

Code:

<arguments>
<arg>-rom</arg>
<arg>sd:/vbagx/roms/GBA/</arg>
<arg>-r</arg>
<arg>2</arg>
<arg>-button_A</a>
<arg>B</arg>
<arg>-button_B</arg>
<arg>Y</arg>
<arg>-button_L</a>
<arg>L</a>
<arg>-button_R</a>
<arg>R</a>
</arguments>

Although I think reduceScale -> 100 would do the same, right?

Yes, It would do, also you can skip:

<arg>-button_L</a>
<arg>L</a>
<arg>-button_R</a>
<arg>R</a>

If you skip a value, mgba will take default ones.

I just have another question regarding the -rom argument.

Do I have to specify the exact ROM (.gba) to be loaded or can I simply specify the folder that I want the app to open up by default instead of the root of the SD?

You have to specify a game path -rom-, not path to a folder game, this option it's for auto booting a game directly from front end like wiiflow, postloader or meta.xml file