Atomized the functionality of the base tomo package

elements/window.go

@@ -0,0 +1,39 @@
+package elements
+
+import "image"
+
+// Window represents a top-level container generated by the currently running
+// backend. It can contain a single element. It is hidden by default, and must
+// be explicitly shown with the Show() method. If it contains no element, it
+// displays a black (or transprent) background.
+type Window interface {
+	// Adopt sets the root element of the window. There can only be one of
+	// these at one time.
+	Adopt (child Element)
+
+	// Child returns the root element of the window.
+	Child () (child Element)
+
+	// SetTitle sets the title that appears on the window's title bar. This
+	// method might have no effect with some backends.
+	SetTitle (title string)
+
+	// SetIcon taks in a list different sizes of the same icon and selects
+	// the best one to display on the window title bar, dock, or whatever is
+	// applicable for the given backend. This method might have no effect
+	// for some backends.
+	SetIcon (sizes []image.Image)
+
+	// Show shows the window. The window starts off hidden, so this must be
+	// called after initial setup to make sure it is visible.
+	Show ()
+
+	// Hide hides the window.
+	Hide ()
+
+	// Close closes the window.
+	Close ()
+
+	// OnClose specifies a function to be called when the window is closed.
+	OnClose (func ())
+}