I have a windows forms control I want to use as part of a custom editor. I created a WPF usercontrol as a wrapper and set my winforms usercontrol as the child of a WindowsFormsHost element. I have a TextBlock in the WPF usercontrol as well, so I can see where the WPF content is and where the winforms content is. I applied an EditorAttribute to a property with the style set to DropDown. The WPF TextBlock is visible, a border around the winforms content is visible, but the winforms usercontrol is not shown. If I change the editor style to Modal, all of the content is shown correctly in the modal dialog. Are there restrictions or known problems with using WindowsFormsHost in an editor with the DropDown style? Thanks - Mitch