Go ahead and install the latest version over the existing version. Back up your profile in case there are any problems. If you don't like the new version, install an earlier version from here. If you use the Lightning calendar, you will have to install a version compatible with your TB version. It is possible to have different versions of TB running the same or different profiles, but that kind of setup is unnecessarily complex for what I think you're trying to do.

Thank you, but I did not ask what you are answering.

Maybe someone else can provide an actual answer to my request, rather than telling me I should do something other than what I want to do?

Thanks.

You need to install the test Thunderbird in an alternative location; by default it will overwrite the existing one (which is what sfhowes' advice was aimed at.)

More problematic is that both versions of Thunderbird will, unless you do something about it, use the same profile and if you want to test an alternative version independently, you'll need to create a copy of your profile (or start over with a new one) and set the new thunderbird to access the copy or new profile. This second bit is probably the harder part of the whole project. It would involve setting up a launcher or shortcut that aimed at the alternative Thunderbird (in its new discrete location) along with a command line switch to select the alternative profile.

Copying your profile and overwriting the existing Thunderbird is actually rather easier.

Or rather than trying to run multiple Thunderbirds independently, you could use an alternative user account for testing; that account would have its own profile and therefore avoid the danger of the new Thunderbird damaging your working profile. (This is how beta testers test Thunderbird. We set it up in a new user account, or in a new instance of the OS in a virtual machine.)

You'd still have to make sure that the old and new Thunderbirds were installed in their own folders so as to avoid the the test version overwriting the standard version. In my beta testing, I install Thunderbird into the user folder rather than the generic location under "Program Files (x86)" or whatever it is called. (specifically, in Linux, I install the test version under ~/opt/Thunderbird, whereas the regular version lives at /opt/Thunderbird.)

If this all sounds like too much hassle, just follow sfhowes' suggestion. Backup your working profile and install the test Thunderbird over the old one. Rewind if you don't like it.

Thanks. That helps. I would just install in a new dir, which I have done in the past. I don't generally install in the default places when given a choice, regardless. But in recent times, TB does more and more stuff behind my back, and I have been bit somewhat below my back by it.

I use multiple profiles anyway, so like I said copying one of them is not a problem. The problem comes in preventing TB from clobbering an existing installation, which can happen either because it doesn't give me any choice where to install once it discovers that TB is already installed somewhere, or when it clobbers windows registry values that I may have changed.

Maybe I should have mentioned that I'm using windows, since the registry becomes an issue.

So, maybe I should refine my question as follows:

If I download the latest version of TB, and put it in a new dir, and run the installer:

1. Will TB give me an option of where I want it installed, rather than silently deciding it should instead update my current install?

2. Will it change any registry values related to TB or other stuff? (For example, which mail client FF starts when I want to email a link -- this is a problem when using FF with "--no-remote" with multiple profiles.)

Now, I could determine that myself by experimentation, but in the past that approach has caused some pain.

--p.

1, yes it is the same custom install that has existed since about version1. I certainly do not recall it changing.

2. Yeas the default mail client will change unless you turn that option off to check on each startup.

But I am with Christ1. a lot of work for very little or no return.

Thanks.

Ok, I think my problem is reduced to making sure that the new install does not run TB before I can run it with -profile <path> , or if I can tell the installer where I want the profile to be kept. Creating a "shortcut" or script that calls TB with the right profile doesn't bother me; it's a triviality.