Inverted/negativeButton in Preview Panel vs Preview area at bottom of Edit View

Scripting
2

Switching the preview:

Font.currentTab.previewView().setBlack_(True)

and setting the panel is a bit more complicated:

for plugin in Glyphs.delegate().valueForKey_("pluginInstances"):
	if plugin.__class__.__name__ == "GlyphsPreviewPanel":
		print plugin.previewView().setBlack_(True)