Back in 2020, I did some work to add accessibility to modalBox, which

involved also ensuring that keyboard input remained restricted to the

box.
This ended up causing crashes when there were multiple boxes on the

screen. Any focus within the latest modalbox would cause a previous

modalbox to steal focus, which would cause the latest to steal focus

back, and so on until the browser crashed the attempt.
This was only noticeable if you had the JavaScript console open, but is

clearly not ideal.
This change updates the behavior to only attempt to steal for the latest

modalbox. Focus management is now performed in a central function, which

only exists once and only while there's a modalbox on screen. An array

of modalboxes is used to track the stack of modalboxes.

Tested the Discard Review modalbox within the Review Dialog modalbox on

both Chrome and Firefox. Verified that focus behavior continued to work,

and that the modalboxes no longer triggered recursion errors during

focus changes or dialog closes.