Hmmm. It looks like Application.Navigate takes two parameters - a URL and a navigation target. The navigation target can either be ntBlank to open in a new tab, or ntPage to open in the current tab.
// Open link in new tab
Application.Navigate('https://www.tmssoftware.com', ntBlank);
// Open link in current tab
Application.Navigate('https://www.tmssoftware.com', ntPage);
Does that help?
if you type Application.Navigate( into your function, you'll see that TNavigationTarget is the type for the second parameter. Then, if you type TNavigationTarget. as you're filling in the second parameter, you'll see these options appear as part of the code completion that pops up. A good trick to use when you're curious about what options are available for methods or types that you might not have used before. Usually much quicker (and more accurate) than hunting through documentation.