User Preference

I have lots of form in my main form and those forms also contain lots of control...like tree, panel..

so when anyone select some font style and color in User preference form it should be affect on all the open form ..so how can i do that so it can affect all the text in all open form controls..

The basic pattern ("Observer") is that you implement a set of events in your preferences class, and have each of the UI elements listen for changes by registering for this event.