I found the answer, i looked into the watin source and found that the InternetExplorers()
method just returns new IECollection(true);
so i looked at the IECollection
constructor and found that WatiN.Core.Native.InternetExplorer.ShellWindows2()
returns all the browsers.
So in the end i did this:
var allBrowsers = new WatiN.Core.Native.InternetExplorer.ShellWindows2().Where(x => x.Visible == false);
foreach (SHDocVw.IWebBrowser2 internetExplorer in allBrowsers)
{
//do somthing.
}