Try this:
add to the head of the xamlfile
xmlns:System="clr-namespace:System;assembly=mscorlib"
Then Add this to the resource section:
<System:Double x:Key="theMargin">2.35</System:Double>
Lastly, use a thickness on the margin:
<Button Content="Next">
<Button.Margin>
<Thickness Top="{StaticResource theMargin}" Left="0" Right="0"
Bottom ="{StaticResource theMargin}" />
</Button.Margin>
</Button>
A lot of system types can be defined this way: int, char, string, DateTime, etc
Note:
You’re right… Had to do some better testing.. changed to code so that it should work