After almost a couple of weeks dealing with problems trying to open an attachment on round cube, I finally found the cause.
The point is I always use English as language on my operating system, and because of that I couldn’t find the bug before, but yesterday night an officemate and I decided to compare the differences between our two set of configurations, and the only difference we found was language, he used Spanish (Español), so I asked him to change language what round cube presents the links to the set of personal settings, well then he pointed to English US and all bugs went away.
Another point discovered is that roundcube does not support any of Internet explorer versions to deal with attachments. But Mozilla Firefox or Opera as explorer does, so they are a very good choice.
So then I would like you to keep this in mind for next releases and I hope I could finally find an answer to all my users that uses Spanish on round cube, by the way I think is the best option once it is based on Ajax. And of course I hope it continues being a successful webmail.
I will look forward to hear from you...
Kiki