I think what you're asking is you want a code-behind file for a ResourceDictionary. You can totally do this! In fact, you do it the same way as for a Window:
Say you have a ResourceDictionary called MyResourceDictionary. In your MyResourceDictionary.xaml file, put the x:Class attribute in the root element, like so:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="MyCompany.MyProject.MyResourceDictionary"
x:ClassModifier="public">
Then, create a code behind file called MyResourceDictionary.xaml.cs with the following declaration:
namespace MyCompany.MyProject
{
partial class MyResourceDictionary : ResourceDictionary
{
public MyResourceDictionary()
{
InitializeComponent();
}
... // event handlers ahead..
}
}
And you're done. You can put whatever you wish in the code behind: methods, properties and event handlers.
== Update for Windows 10 apps ==
And just in case you are playing with UWP there is one more thing to be aware of:
<Application x:Class="SampleProject.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:rd="using:MyCompany.MyProject">
<!-- no need in x:ClassModifier="public" in the header above -->
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<!-- This will NOT work -->
<!-- <ResourceDictionary Source="/MyResourceDictionary.xaml" />-->
<!-- Create instance of your custom dictionary instead of the above source reference -->
<rd:MyResourceDictionary />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
Instead of putting (as in your example) a button directly on the canvas, you could put a stackpanel on the canvas, horizontally aligned, and put the two buttons in there.
Like so:
<Canvas>
<StackPanel Canvas.Left="100" Canvas.Top="100" Orientation="Horizontal">
<Button>Button 1</Button><Button>Button 2</Button>
</StackPanel>
</Canvas>
I think that it's quite flexible when you use more than 1 layout in a form, and you can create pretty much any configuration you want.
Best Answer
If you want to center the controls you could wrap them in a grid:
Other positioning can be accomplished by other panels like StackPanel etc. Grid beeing the most flexible choice.
Edit: updated with grid and columns for controlling position: