Comment # 8 on bug 1084017 from Jiri Srain

I'm a bit hesitant to change the values automatically - but on the other hand
for users not knowing the details, this can lead to situations like this.

I would consider: When changing the Stage1 location from MBR to partition, ask
user whether to put the generic code to MBR and activate the partition - unless
those check-boxes are already checked.

This should give users enough hints while avoiding the surprise of rewritten
MBR.