As per the API documentation, setting the stroke width to 0 should still leave a hair-line stroke around the shape and should not entirely remove the stroke. Here is what is given in the API Doc -

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A value of 0.0 specifies a hairline stroke.
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I see this happening properly on Desktop but on Mobile, the stroke completely disappears when setting the stroke width to 0. To reproduce the bug, deploy the attached application on the emulator using JavaFXPackager and do the following -

1. Press '1' a few times to choose 'Stroke-only' mode
2. Press '3' a few times to choose a darker stroke color
3. Press '6'. This will increase the stroke width. After reaching 20, it resets to 0.
4. Now check if you see a hair-line stroke. If it is not shown, it is a bug.

I reproduced it on WinXP SP3 - JavaFX SDK 1.0.1-b02.