On Windows Store 8.1, Buttons are displayed with a visible Border, even though BorderWidth is set to 0.
The following is a dump of relevant properties of a Button in my app. The BorderColor is set to Color.Lime, but with both BorderWidth and BorderRadius set to 0, a Lime colored border is still displayed. With BorderWidth set to 0, I would not expect to see a border at all.
Text = "RNo",
TextColor = [Color: A=1, R=0, G=0, B=0, Hue=0, Saturation=0, Luminosity=0],
BackgroundColor = [Color: A=1, R=0.752941191196442, G=0.752941191196442, B=0.752941191196442, Hue=0, Saturation=0, Luminosity=0.752941191196442],
BorderColor = [Color: A=1, R=0, G=1, B=0, Hue=0.333333343267441, Saturation=1, Luminosity=0.5],
Margin = (12,12,12,12),
BorderWidth = 0,
BorderRadius = 0,
Height = 38
The same happens on UWP as well.
*** Bug 30313 has been marked as a duplicate of this bug. ***
Should be fixed in 2.3.4-pre1. Thank you!