Advice request on how to handle change in how Konqueror stores login information

[Stefano Crocco]

Hello to everyone,
I'd need an advice on how to proceed with a change I'm going to make in 
Konqueror which could lead to data loss for the users. To improve the way 
Konqueror auto-fills login information in web pages, I had to change (in a way 
which depends on the page content) the name of the entries it uses to store 
login information in KWallet. As a consequence, existing entries won't be 
recognized anymore and users will have to enter them again the first time they 
visit a page so that entries with the new names can be created.

In theory, this shouldn't be more than an annoyance for users, but I'm 
worried that there could be people who only relied on Konqueror to fill 
passwords and didn't record them somewhere else: in this case, they couldn't 
easily access their passwords anymore.

I've thought of three possible ways to proceed:
- ignore the issue. This is, obviously, the easiest choice but also the most 
user-unfriendly
- display a KMessageWidget with information on how to recover the login 
information from KWallet when the user tries accesses a page with login 
information stored in the old way
- automatically rename entries when the user accesses a web page with stored 
login information. This is the more user-friendly approach, but also the more 
complex to code; besides I fear that there's no way to determine which form on 
a given page corresponds to the data in the wallet which is correct in every 
situation
- display a warning the first time the new Konqueror version is launched 
describing the situation and how to manually retrieve login information from 
KWallet. This could be a decent compromise between user-friendliness and ease 
to code, but I'm not sure what is the best way do display the warning: would a 
simple message box be suitable?

What do you think would be the best way to proceed?

Thanks in advance.

Stefano