atomx: WM_CLASS only returns the instance value (not class) about core HOT 2 OPEN

Agreed. An example I found was picom expected class from your example when defining classes e.g. for opacity rules.

from core.

It seems like the atom value returned sends the class and instance terminated with a nullbyte. Currently atomx simply prints the value with printf(3), so the first nullbyte (after the class name) marks the end of the string. Printing the instance name would require printing the whole data returned, either by writing the full data to stout (including the intermediate null bytes), or iterating through the whole data, and reformatting it. Not sure how it should be formatted though (tab separated, new line, ...?).

from core.