Question

Two buttons:

    <Button Content="Button" Height="72" HorizontalAlignment="Left" Margin="10,10,0,0" Name="button1" VerticalAlignment="Top" Width="160" Click="button1_Click" />
    <Button Content="Button" Height="72" HorizontalAlignment="Left" Margin="10,92,0,0" Name="button2" VerticalAlignment="Top" Width="160" />

Self explanatory code:

    public MainPage()
    {
        InitializeComponent();
        button1.Background = new SolidColorBrush(Colors.Red);            
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        Color c = ((SolidColorBrush)((Button)sender).Background).Color;

        if (c == Colors.Red)
        {
            c = Colors.Green;
        }
        else if (c == Colors.Green)
        {
            c = Colors.Blue;
        }
        else if (c == Colors.Blue)
        {
            c = Colors.Red;
        }
        else
        {
            c = Colors.Yellow;
        }

        ((Button)sender).Background = new SolidColorBrush(c);
        button2.Background = new SolidColorBrush(c);
    }

In an ordinary Silverlight app everthing works exactly as expected. However, in Windows Phone 7 the exact same code behaves as follows:

button1 does not change color (it just stays red)
button2 does change color unless I click it in which case it no longer changes color when I click button1 (i.e. its color is now stuck as well)

clue enyone?

Answer 1

Following should do the trick:

var btn = sender as Button;
var brush = ((SolidColorBrush)btn.Background);

if (brush.Color == Colors.Red)
    brush.Color = Colors.Green;
else if (brush.Color == Colors.Green)
    brush.Color = Colors.Blue;
else if (brush.Color == Colors.Blue)
    brush.Color = Colors.Red;
else
    brush.Color = Colors.Yellow;

btn.Background = brush;
button2.Background = brush;