[XFCE] Increase window resize grip area

[d-packs]

OS: Antergos Linux x86_64
Kernel Release: 4.19.20-1-lts
WM: Xfwm
DE: Xfce 4.12
RAM: 2169 MB / 11631 MB
Processor Type: Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz

Currently, resizing windows in XFCE using Numix-Frost Light is a huge pain, as it's difficult to hit the 1px wide window border with the mouse to click it and drag to resize the window (both vertical and horizontal borders are affected).

Making it a more accessible width would greatly increase the usability of the theme. I have tried modifying the files of the theme in the gtk-2 and gtk-3/gtk-3.20 folders myself, to no avail.