When DT2 can’t recognize the file type, and you ctrl click and choose Open With, there is a problem if the system doesn’t know what application to use to open this file type, because all it says is .
When this happens with other apple applications or in finder, it does say , but under this is the Other option, which allows you to use finder to pick an application to use.
DT2 should function like this, and add the Other option.
I had text files which had a unique extension, and ran into this problem.