Checkbox: SetText and better BoolVar watch for CheckButton

check_button.go

@@ -61,6 +61,14 @@ func (w *CheckButton) Compute(e render.Engine) {
 		} else {
 			w.SetBorderStyle(BorderRaised)
 		}
+	} else if w.BoolVar != nil {
+		// Checkbutton, always re-assign the border style in case the caller
+		// has flipped the boolean behind our back.
+		if *w.BoolVar {
+			w.SetBorderStyle(BorderSunken)
+		} else {
+			w.SetBorderStyle(BorderRaised)
+		}
 	}
 	w.Button.Compute(e)
 }

checkbox.go

@@ -1,5 +1,7 @@
 package ui
 
+import "errors"
+
 // Checkbox combines a CheckButton with a widget like a Label.
 type Checkbox struct {
 	Frame
@@ -60,6 +62,14 @@ func (w *Checkbox) Child() Widget {
 	return w.child
 }
 
+// SetText conveniently sets the button text, for Label children only.
+func (w *Checkbox) SetText(text string) error {
+	if label, ok := w.child.(*Label); ok {
+		label.Text = text
+	}
+	return errors.New("child is not a Label widget")
+}
+
 // Pass event handlers on to descendents.
 func (w *Checkbox) Handle(e Event, fn func(EventData) error) {
 	w.button.Handle(e, fn)