My need screencapture is this: I need to screenshot a dualview desktop, each 1920x1080. Total = 1920x2160 (one on top of the other).
You are right. The problem lies on the moment of disk access.
I found a solution. Making an async call (libxprocess>ProcessExecuteAsync) to an external screenshot.exe, to wich I send the path I want it to save the jpeg file.
Works perfectly!!
Now I just have to find one screenshooter that works fine as well on Linux (Wayland).