How to use "Icon Variants" for scripts or IMGUI?

[Neonage]

I want my script icon to have variants for each theme, I found only this info in random documentation:

“Variants must be in the same folder as the default icon, and must have the same name, with specific text prepended or appended. If a has d_ prepended to its name (for example, d_MyWindowIcon.png) Unity uses instead of the default icon when the professional theme is enabled. If a variant has @2x appended to its name, before the file extension (for example, @@MyWindowIcon@2x.png@@), Unity uses it when you run the Editor on HiDPI devices.”

Unity finds and uses variants automatically. If it cannot find the variant it needs, it uses the next closest variant. If no variants exist, Unity uses the default icon.

So it’s the same as with UI Elements? Let’s try:

It actually works for “On” icon…

But once I switch theme, “d_” icon is ignored

How do I deal with it properly?

[Neonage]

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