libc.prctl not available, firefox window resized smaller than space

[red-uk]

great app, thank you. couple of questions:

on running x-tile h the command runs but returns:

libc.prctl not available, the process name will be python and not x-tile
I think this is informational/benign.

Also when tiling Firefox window using h or v, the window is positioned in the correct location, but is resized too small - has space around each side (this doesn't appear happen with other application's windows eg chromium)

running x-tile 3.3 on Kali 2022.3 and Firefox 91.11.0esr (64-bit)

Thanks for any help you can offer.