Stax tests fail when presenting 8 screen itens

[enriquefynn]

The stax tests fail when we have msg->numScreens = 8 or more.
The problem is not the amount of screens shown in stax, but somehow if there are 8 itens in the screen or more, it fails with:

...
[*] patching svc instruction at 0x40015668
[*] patching svc instruction at 0x40015676
[*] exit called (255)

We did a small POC forking the repo and adding 8 screens at https://github.com/ChorusOne/stax-failing-poc