Help me clear my canvas layers!

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Hello,

I’m working on a channel that needs custom player controls, so I’m using an imageCanvas and a videoPlayer. I can paint the controls (png files) and they show up correctly; but I simply cannot get them to go away. They persist even after I sideload the channel! Here’s the instantiation:


            player = createObject("roVideoPlayer")
            canvas = createObject("roImageCanvas")
            port   = createObject("roMessagePort")
            canvas.setMessagePort(port)
            player.setMessagePort(port)
            player.setDestinationRect(canvas.getCanvasRect())

Then later, I go to put the controls on the screen (simplified here):


                addButton: function (button_name)
                    url = invalid
                    if button_name = "pause"
                        url = "pkg:/assets/images/btn-pause.png"
                    else if button_name = "play"
                        url = "pkg:/assets/images/btn-play.png"
                    end if
                    if url = invalid
                        logger("warning", "unknown UI button " + button_name)
                        return invalid
                    end if

                    x1 = m.displaySize.w / 2 - 40
                    y1 = m.displaySize.h * 3 / 4 - 38

                    button = { TargetRect: { x: int(x1), y: int(y1), w: 80, h: 76 }, url: url }
                    m.canvas.setLayer(0, [button])
                    m.canvas.show()
                end function

But there’s no combination of clear(), sleep(), clearLayer() &c. that does anything. And as I said, even if I go into a different channel, and then reload my custom code again, the same canvas persists. What’s going on? Do I need to use a different imageCanvas? Is there any way to control the z ordering of my canvases, other than lexically? I guess I could create and close new canvases every time I needed to paint the chrome?

EDIT: It’s not simply the setLayer() that persists; I stop() the channel, and then in the debugger do an addButton(1, “foobar”) – and that button persists!

TIA.