I ran into this when trying to set a Rich Text Editor’s border to a different color when it was disabled. To my horror, the rich text editor doesn’t the DisabledBorderColor property! If statement to the rescue. I set an If statement on the border property to change it depending on it’s where it was disabled or not. It was clean, easy. You can also other items properties or variables to change fields that “don’t exist”.
My BorderColor formula: If(Self.DisplayMode = DisplayMode.Disabled, Gray, RGBA(0, 18, 107, 1))