Hello, Dave.

Thank you for contacting us.  I think you mean to replace whatever web page you are currently viewing.  There is no way to do that in the current verison of Markster or BookMacster.

I just did a little test and found that it would probably be possible for us to add a feature like that.  I say "probably" because it involves sending Safari an AppleScript command, which, you never know nowadays, Apple might have erected some more security roadblocks which make it unreliable.  Nonetheless, I have entered a task to see if we could add such a feature in Markster/BookMacster version 3.  Probably you would hold down the option key or something like that.