How Record 16:9 (1920x1080) out of 21:9 (2560x1080)?

[mrg]

How to record a screen region of 16:9 (1920x1080) out of a 21:9 (2560x1080) desktop?
I have tried to use 'Active desktop region' mode, but it is not possible because the recording bar is only below the recording region.

[mrg]

After a week with no response, I would like to ask again. Is it really not possible with Action! to record a defined area of exact 1920x1080 pixel out of a desktop with 2560x1080 pixel?