shapes example hangs

`cargo run --example shapes --features="renderer"` creates a window but it does not draw anything.
I had to comment out two occurences of `window.request_redraw();` to make it work.
All the other examples work normally.

Run `cargo run --example shapes --features="renderer"` and inspect the shapes example around its two `window.request_redraw();` occurrences. Done means the example window draws its shapes without hanging, while the other examples continue to work normally.

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