update()ing on system color change

[Jamboarder]

When the plasma theme doesn't supply a "colors" file, plasma uses the current KDE color scheme.  So I've been trying to find a simple way to have all the plasma "thingies" that display something to update() when the user changes the color scheme from System Settings (ONLY if the theme "colors" file wasn't supplied).

I originally thought I would add a slot in Plasma::Applet to update() when the color scheme changed. This worked, until I realized that not all displayed plasma "thingies" were applets.  So, of course, not everything updated (desktop icons, taskbar items, etc.).  Short of going around to all the plasma "thingie" classes, is there a more central place that this could be done?