title: kivy: why cannot I change the color of my rectangle?
body: <p>Here is a method that is supposed to draw the canvas of a label:</p>
  
  <pre><code>def update_canvas(self):
      c = self.canvas.after
      c.clear()
      with c:
          Color([1, 1, 1, 1])
          Line(points=[self.point_from, self.point_to])
          if self.texture:
              Color([1, 0, 0, 1]) # RED RECTANGLE!
              Rectangle(pos=self.pos, size=self.size)
              Color([1, 1, 1, 1])
              Rectangle(pos=self.pos, texture=self.texture, size=self.texture.size)
  </code></pre>
  
  <p>The label used as a tooltip which also has a line pointing to the tooltipped item. The above version produces this output:</p>
  
  <p><a href="https://i.stack.imgur.com/Ru0eh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ru0eh.png" alt="enter image description here"></a></p>
  
  <p>If I comment out the Rectangle instruction after the RED COLOR line, this is displayed:</p>
  
  <p><a href="https://i.stack.imgur.com/piNuU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/piNuU.png" alt="enter image description here"></a></p>
  
  <p>Please note that the text's label is rendered twice, because I have also added a Rectangle(texture=self.texture) instruction, but that is for testing only.</p>
  
  <p>The Label itself is added to the window with this simple call:</p>
  
  <pre><code>Windows.add_widget(label)
  </code></pre>
  
  <p>The question is this: why is my rectangle not red? (Actually I want it to be half transparent.)</p>