Restyling ComboBoxI dropdown gray and not selectable when ComboBox is ReadOnly

I have seen this post: WPF ComboBox: background color when disabled and some others...

But This solution causes me some problems. All I want is to make the textBox gray, and the ComboBoxItems gray and not selectable. I don't want to recreate all the styl开发者_JAVA百科e as the control won't work properly on both XP and seven. I don't want to choose one style for both, but I want XP style for XP and seven style for seven.

Is there a way to set the style so I can change the Background of the ComboBoxItems when the comboBox is Readonly?

Thanks in advance!

Update: It seems that the Drop down popup should be restyled instead. I got to find how.

I finally found my answer at many places on the web, pieces by pieces. The ComboBox style is composed of other controls. The PopUp is the one that interests me. It is not public, so I can't modify it as I want. It would have been interesting to define a style for my popup and to replace the original popup by it, but it is not accessible, so... I attempted to make a template that inherits from the template of the original ComboBox, but that is not possible neither. It won't accept inheritance for some good reasons How to Inherit a Control Template. So the template must be remade totally or not. The other option would be to make my own control that inherits from combobox and that changes the items to gray and not selectable when the combobox is readonly (into the code), but this is not a good idea in my situation. No solution for me. I will have to stick with the whole template redifinition. I hope this post will help someone in some way!