ThemedDialogStyleLoader.SetUseDefaultThemedDialogStyles() can fail in the designer. It seems that this is caused by the resource VsResourceKeys.ThemedDialogDefaultStylesKey not always being found. I've wrapped the entire dependency property change handler in a design-mode check so that the property has no effect in the designer.
ThemedDialogStyleLoader.SetUseDefaultThemedDialogStyles()
can fail in the designer. It seems that this is caused by the resourceVsResourceKeys.ThemedDialogDefaultStylesKey
not always being found. I've wrapped the entire dependency property change handler in a design-mode check so that the property has no effect in the designer.