An integer value in WPF Resources?
Solution 1:
To make that declaration you need to import the System namespace:
xmlns:sys="clr-namespace:System;assembly=mscorlib"
...
<sys:Int32 x:Key="MyValue">1234</sys:Int32>
Note: you will need to use a Double for most WPF properties instead of an Int32
Solution 2:
For StrokeThickness it should be
<system:Double x:Key="ThemeIconStrokeThickness">1</system:Double>