Child of WindowsFormsHost inside materialDesign:DialogHost.DialogContent not visible.

まだ誰も着手していません。

### Bug explanation

Hello everyone!

I want to use a WindowsFormsHost as Content inside of a DialogHost.

Unfortunately the added child element of the WindowsFormsHost is not visible, but i can interact with it (e.g. the contextmenu opens when rightclicking on an inputmask)

Do you have any ideas how i can achieve to see the child of the WindowsFormsHost ?

Best wishes

Gabriel

### Version

4.9.0

Start by reproducing the issue described with WindowsFormsHost as content inside materialDesign:DialogHost.DialogContent on version 4.9.0. Inspect the interaction between these two controls and verify that the WindowsFormsHost child becomes visible while remaining interactive, including its context menu.

索引モデルが issue の本文から書いたものです。