how to highlight/select text in a wpf textbox without focus?

I want to highlight selected text in a wpf textbox while the textbox is not focused. In my application, my textbox never gets focus, and every key input is done manually.
I was wondering if there is a way to highlight the selected text when the textbox is not focused?
Any help would be appreciated!

Are you using MVVM? If so you can use the attached property pattern to accomplish this. If not you can use code behind. Both methods will use INotifyPropertyChanged implementations and should bind to the property on the control that controls the highlighted text.