When you create a new memory and join some other memories (I did this to create a huge TM out of other TMs and to backup it), the memory is not saved
But in the tab you see (resp. saw) that there are 20.000 segments (to say a rather low number). And – if I am not mistaken – you are asked for any other memory if you want to save it or not before exiting.
I suppose that the TM will be saved as soon as x segments have been changed (the standard behavior for other TMs) – but will then happen to joined read-only memories? Yes, you can actively save the memory, but this is not an expected behavior.
Of course there is one minor advantage of this behavior: if you want to avoid a larger undo process if you selected the wrong TM to join.
Shouldn't there be a prompt to avoid this behavior (also for many other cases with other TMs, where they have been changed in any manner)?
There should be
Yes, the prompt when closing the TM tab of joined TMs or saving it automatically when exiting is there in the latest build (2017052501). Thanks!