I have had gtk theme switcher hang.
I seems more likely to hang if rox is open
Here are the steps
Open terminal and start top
Open rox
Change desktops
Open Puppy desktop/theming/GTK theme switcher and pick a new theme click ok
If the theme switcher closes check top
I have a dual core processor and one is usually at 100%
Top will show 1 zombie process "gtkdialog"
-----------------PC-----------------------------------------
Mfg: Dell Inc.
Model: Vostro 220 Series
Arch: x86_64
CPU: Pentium(R) Dual-Core CPU E5200 @ 2.50GHz
Mem: MemTotal: 3981372 kB
HD: 149G
Screen: 1280x1024 60.02*+ 75.02
-----------------OS-----------------------------------------
Puppy: "Vanilla Dpup 9.3.6"
Version: 9.3.6
OS: GNU/Linux
Kernel: 5.10.162