[Feature Request] Import Titlebar Icons from Another Installed Theme

[Nano-Ocelot]

A great example of this feature is in this applet here. https://github.com/psifidotos/applet-window-buttons

There's a dropdown that lets you choose the button icons from any installed window decoration. This way I and others can use the great customization features of this window decoration without having to sacrifice the icons that we prefer.