I created small tmux pane.
After that I call

ps -AF | grep lightdm

Output is empty.

If I maximize pane, output is:

root      251265  0.0  0.1 2928400 131360 tty7   Ssl+ 19:58   0:01 /usr/lib/xorg/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch

Output depends tmux pane size.
How? Does horizontal tmux buffer truncate the output?