// Bubble draws a text balloon.
func Bubble(gc draw2d.GraphicContext, x, y, width, height float64) {
sx, sy := width/100, height/100
gc.MoveTo(x+sx*50, y)
gc.QuadCurveTo(x, y, x, y+sy*37.5)
gc.QuadCurveTo(x, y+sy*75, x+sx*25, y+sy*75)
gc.QuadCurveTo(x+sx*25, y+sy*95, x+sx*5, y+sy*100)
gc.QuadCurveTo(x+sx*35, y+sy*95, x+sx*40, y+sy*75)
gc.QuadCurveTo(x+sx*100, y+sy*75, x+sx*100, y+sy*37.5)
gc.QuadCurveTo(x+sx*100, y, x+sx*50, y)
gc.Stroke()
}