Is it normal/just for a software company to ask for power of attorney to ensure they obtain patents on anything you invent while you are employed as a programmer?
In my case, I went back the the employer. They told me they have no interest in using my inventions which are not related the domain that were not invented during company hours, using company resources.
The company encourages open source contribution, and will not interfere in that regard.
I further examined the contract, and at the point where the term 'inventions' is defined in legal speak, it stated that inventions in the context of this agreement were only those developed using company resources within company time.
Power of Attorney allows the company to ensure they can get my signature (or equivalent in my absence) for any inventions which they may wish to patent.