How long did it take to make your WinXP App Vista-Compatible?

"The question you're asking appears subjective and is likely to be closed."
Yes this is a subjective question.
It has no answer.

I was just wondernig if I was the only one.
So... was it painful?
I just want to hear some comments.

Jag

P.S. Of course, it all depends on the app size, the language it was written, good or bad programming habits, etc...

From stackoverflow

• Very painful, and a cost of several days if not weeks over time...

  We had a lot of code revolving around sessions and IPC. So we were effected by the change of session 0 isolation.

  For Vista x64 and 2008 x64 we also had some driver components that needed to be digitally signed with authenticode now. Which wasn't a requirement before.

  We also ran into some trouble with some of our apps not having manifest files to specify that they needed to be run as an elevated process.

• I had to move some registry keys from HKLM to HKCU - that was all - and I was very happy about that. About an hour or two. Less than a day form when it was discovered to when we had it fixed and in the source tree. Not sure of the line count on that C++ app.

  Not huge, but not trivial

• Not much. I worked primarily on a large app written in C++ and MFC. We moved to VS 2008 before Vista (waiting for VS 2008 SP1, which saved a lot of trouble), and most things just simply worked. There was one external library I found a slight problem with (compensating for old VC++ problems), but no big deal.

  Except for a routine to grab a window and put it into JPEG format, which I narrowed down to a small stretch of standard code that was vetted by competent people both here and on the MSDN forum. Eventually, that problem went away on my computer, so I couldn't pursue it, but it has cropped up on others.

  So, I never know when the goblins are going to come and take the JPEGs away, but other than that the transition to Vista was smooth.