[Eric] Generate dialog code

[Gertjan Manenschijn]

After changing an ui file i want to regenerate my dialog code. So i 
right-click on the ui file and choose generate dialog code.
Then i can only choose new classname, but i want to update an already 
existing class. If i choose new class and give it the same name as the 
old class, then
the old class is overwritten and i lose my code. Is it possible to 
update the old class without losing my code?

Regards,
Gertjan