Some properties carry over across themes - like the icon position. If you switch theme, change the icon position, then switch back, you'll notice that the icon position is kept to it's last setting. If you switch theme, change the font and font size, then switch back, the font properties don't keep the last selected value - they keep the last selected value for each theme, allowing you to select a different font for iOS and android. It's assumed that the icon should stay the same, so the icon font name and size (or the image id) are retained when the theme changes - the same way as the icon position. I'm hoping that this is the correct way for the control to behave for most circumstances, but maybe more options will be required in the future to change which properties are retained between themes (and which aren't) by default.