Custom WPF user control via repositionable child control

I need your help.

I would like to develope a WPF user control via these features: 1. Control should be able to have a content. 2. We should be able to define a position at parent control, where child control should be rendered.

It doesn't seems to be a difficult case, but I insistently can not find any helpfull information. Any information appreciated - I am only begining to learn WPF.

Thanks is advance. :)

[Update]

1. In "开发者_如何学CHost control" - PartSelectorList:

   1.1. Xaml: < ContentControl Content="{Binding Path=Dummy}" Height="50" Visibility="Visible" />

   1.2. Code-behind: DependencyProperty DummyProperty

2. In "Final control":

   2.1. Xaml: ...

   < PartSelectorList>

   < PartSelectorList.Dummy>

   < StackPanel />

   < /PartSelectorList.Dummy>

   < /PartSelectorList>

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why not do something really simple

<ContentControl Canvas.Left="10" Canvas.Top="20"> ..content here</ContentControl>