btnaction

type IWidget interface {
	SetLabel(string)
	Show()
	Hide()
}

type Tune interface {
	// Set... sets the button state.
	//
	SetNone()   // hide the action button.
	SetSave()   // show the action button with save text.
	SetApply()  // show the action button with apply text.
	SetAdd()    // show the action button with add text.
	SetGrab()   // show the action button with grab text.
	SetCancel() // show the action button with cancel text.
	SetTest()   // show the action button with test text.
	SetDelete() // show the action button with delete text.

	// Display displays (or hides) the button as configured.
	// This will reapply the last known state.
	//
	Display()

	IWidget // Extends a gtk.Button, or other gtk.IWidget with SetLabel.
}