src/vs/platform/theme/common/themeService.ts/ThemingRegistry/onColorThemeChange
class ThemingRegistry:	public onColorThemeChange(participant: IThemingParticipant): IDisposable {
		this.themingParticipants.push(participant);
		this.onThemingParticipantAddedEmitter.fire(participant);
		return toDisposable(() => {
			const idx = this.themingParticipants.indexOf(participant);
			this.themingParticipants.splice(idx, 1);
		});
	}