Use system default theme setting is invalid

[witt-bit]

This problem did not exist when I first installed guake. By chance, I switched the system from dark theme back to light theme, and guake could not detect this change and always kept the light theme.

Now no matter what I try, it can't detect it

$ guake --support                                                                                                  ✔ 
<details><summary>$ guake --support</summary>

Guake Version:		3.11.dev0

Vte Version:		0.76.4

Vte Runtime Version:	0.76.4

--------------------------------------------------
GTK+ Version:		3.24.43

GDK Backend:		<GdkX11.X11Display

--------------------------------------------------
Desktop Session: plasma

--------------------------------------------------
Display: :0

RGBA visual: True

Composited: True

* Monitor: 0 - CMN eDP-1
    * Geometry:		1920 x 1080 at 0, 0
    * Size:		309 x 173 mm²
    * Primary:		True
    * Refresh rate:	60.007 Hz
    * Subpixel layout:	unknown

[Davidy22]

Doing some messing around with it, some observations:

• Prefer dark theme checkbox overrides the system default option
• System default setting updates when the checkbox is clicked or guake starts up, not when system theme changes

Prefer dark theme checkbox should probably be logically lower priority than the system default checkbox, especially since it grays out when you check the other one. Looking into gnome system wide signals to hook into so that we can do the theme update on times other than just when you click the checkbox.

[Davidy22]

After more testing and observations, my initial observations were wrong and I was just looking wrong, themes were updating right when switching in tweak tool