When running the InterpreterSimulator I get two doesNotUnderstand
errors, one after the other.  Below is a partial call stack of each:

SecurityPlugin>>doesNotUnderstand: #ioCanWriteImage
SecurityPlugin>>primitiveCanWriteImage
InterpreterSimulator>>callExternalPrimitive:
...

SecurityPlugin>>doesNotUnderstand: #ioGetSecureUserDirectory
SecurityPlugin>>primitiveGetSecureUserDirectory
InterpreterSimulator>>callExternalPrimitive:
...

Both ioCanWriteImage and ioGetSecureUserDirectory are missing in
SecurityPlugin, although ioCanWriteImage is defined in
InterpreterSimulator.  Looking them up in the VM source, I find both
defined in unix/sqUnixSecurity.c.  ioCanWriteImage is also defined in
sq.h as a constant 1 (true).

Where should these methods be placed in the simulator?  Do we need a
subclass of SecurityPlugin called SecurityPluginSimulator and put these
method there?  This would be awkward, but they can't go directly in
SecurityPlugin because then they will be included in the C translation. 
They also don't belong in InterpreterProxy or InterpreterSimulator
because the SecurityPlugin does not look for them there.

Image version: Squeak3.1alpha of 27 February 2001
latest update: #3812
VM version: Squeak3.1alpha of 27 February 2001 [latest update: #3776]
for: unix

Also, even after implementing temporary methods for these in SecurityPlugin, my simulated image won't highlight the active window or accept input.  I'm openning a small (3MB) MVC only image in the simulator.

-Anthony