When I use Thunar as root, it says "Warning, you are using the root account, you may harm your system." This is grammatically incorrect. The correct punctuation would be "Warning: you are using the root account. You may harm your system."
Mousepad shows that warning message too. https://git.xfce.org/apps/mousepad/tree/mousepad/mousepad-window.c#n870
Andre Miranda referenced this bugreport in commit a240092b8f8fc93fe5acc7b49f47383b09414d30 Fix message punctuation (Bug #16783) https://gitlab.xfce.org/xfce/thunar/commit/a240092b8f8fc93fe5acc7b49f47383b09414d30
Same change applied to Mousepad, thanks for pointing it out.