Thanks for your report. I tried V1.7 dev (today version). In my environment, some installation warnings were displayed. And, default editor did not work, too.
Warning: array_fill() [function.array-fill]: Number of elements must be positive in ***\qa-include\qa-db-install.php on line 541
Warning: array_combine() expects parameter 2 to be array, boolean given in ***\qa-include\qa-db-install.php on line 541
Uncaught TypeError: Cannot set property 'dir' of undefined
Because this version is for development, there will be still many issues. We should not use the development version that is not released formally.