Remove completed TODO.
Store override ROM path as property.
Prep. for validating ROMs.
Fix bad references.
Update status text when validating data.
Rename function.
Update rom-header read method.
Validate that ROM has valid header.
Prep. for handling failed file validation.
Update status messages on successful validation.
Fix calls to callbacks.
Remove variable accidentally logged.
Do not log which file is being validated.
Rephrase log message.
Re-enable drop zone if file does not validate.