Synchronisation problems with concurrent modifications

[marinabilles]

I have noticed a few problems due to making concurrent modifications by opening the same document on two clients with different user accounts and making conflicting edits. The conflicts are improperly resolved. This can be reduced easily with a single person, as the time to synchronize the modifications takes a lot of time in the Documents app anyway.

Consider a document containing only the character "a". Client 1 types another a, while Client 2 selects the text and makes it bold. After synchronization, the extra "a" that gets synchronized does not appear bold on both clients, only one of them. The same effects can be seen with other font changes such as font size or font face.

Also, consider a document with no content and select the font face Verdana on Client 1. Then, on Client 1 type "a" and on Client 2 type "b". Again the synchronized extra "b" is not formatted

Server:
Ubuntu 16.04
ownCloud 9.1.3
Documents app 0.9.2

Client:
Ubuntu 16.04
Firefox ESR 45.5.0