Sometimes this gets left behind (it is not always removed by app), too - AppData\Roaming\Thunderbird\Crash Reports\InstallTime .*
And, it does not seem to clear this automatically when found, on restart.
On the other hand,
Firefox 15.0.1 creates and removes this folder, [AppData\Roaming\Mozilla\Extensions].
One thing I noticed is that Thunderbird creates a separate folder for
AppData\Roaming\Thunderbird\Crash Reports\InstallTime .*
Meanwhile,
Firefox uses AppData\Roaming\Mozilla\Firefox\Crash Reports
And,
AppData\Roaming\Mozilla\Extensions-BackupByFirefoxPortable
I thought that it might have been a conflict with having firefox running at the same time, but that is not the case.
As I have been using Maxthon recently, and I tried running and closing thunderbird when firefox not in use and the folder is left behind.
The only reason either of these happen is if your PC crashes and all apps crash with it. Or if you shutdown Windows without closing your apps, which is the same as the apps crashing.
Sometimes, the impossible can become possible, if you're awesome!
No, I just tried it again.
Closed Firefox
Ran Thunderbird,
and on exit Mozilla\Extensions got left behind
Also, when this folder is left behind,
on exit Firefox sometimes removes this folder and sometimes it does not,
removing only these folders
AppData\Roaming\Mozilla\Firefox\Crash Reports
And,
AppData\Roaming\Mozilla\Extensions-BackupByFirefoxPortable
while leaving behind Mozilla\Extensions
It is strange that sometimes Firefox it removes all folders ( including base folder left behind by thunderbird ) and sometimes no
Thunderbird always leaves behind Mozilla\Extensions
Sometimes it leaves behind AppData\Roaming\Thunderbird\Crash Reports\InstallTime .*
And it does not remove it on next Run, shouldn't it?
Firefox removes Mozilla\Extensions .
But, when Firefox starts with the folders Mozilla\Extensions already there
Sometimes it removes all folders, sometimes it leaves Mozilla\Extensions behind, since it was already created I presume.