bugs need additional fields

i'd like to use this tool as my bug tracking device as well, but bugs need some additional information to be useful. the following fields are using in a tool called mantis:

ID:
Category:
Severity:
Reproducibility:
Date Submitted:
Last Update:
Reporter:
View Status:
Assigned To:
Priority:
Resolution:
Platform:
Status:
OS:
Projection:
OS Version:
ETA:
Fixed in Version:
Product Version:
Target Version:
Product Build:
Summary:
Description:
Steps To Reproduce:
Additional Information:
Tags:

Although not all of them apply, some fields like this (or custom fields) would be really useful in this tool.