... since the customize dialog would not disappear when clicking "done" button
I saw your announcement of MacHg on hg's mailing list and just started to test it a little.
First of all I want to say that I am impressed by its looks. :)
Well, I used Murky for a while, but will give MacHg a go from time to time to help improving it, if I find enough time to post my issues here.
Good luck with this project of yours Jason!