Chadwick Wood

I'm making a patch that can monitor which window is active, and do things when the active window changes. To do this, it polls the max.frontpatcher property to see which Patcher is active. It stores a reference to that Patcher as the "active" patcher, and goes on polling.

What I've noticed is that if I run this patch, then open another patch (any patch, it doesn't matter what is in it, even a new blank patch), then my patch registers that patch as "active". As soon as I close that patch, Max crashes.

I think the crash is happening specifically when my code tries to check the "name" property of that active patch that is now closed... it must be trying to access freed memory or something. But as far as I can tell there's no sort of "valid" property on a Patcher object to tell if that Patcher still exists or not, so I can't figure out a way around this. Below is my JS code, and attached is a small patch that opens the JS and will demonstrate the bug if you open another patch and close it while this patch is open.

function checkFront() {
  var front = max.frontpatcher
  if (!front) { return }
  if (!activePatcher || activePatcher.name != front.name) {
    activePatcher = front
    post(activePatcher.name)
    post()
  }
}

var task = new Task(checkFront)
task.interval = 500
task.repeat()


RefBug.zip

I'm making a patch that can monitor which window is active, and do things when the active window changes. To do this, it polls the max.front

max-crashes-when-patcher-is-closed-and-js-holds-a-reference-to-it

This definitely looks like a bug in Max – it shouldn't crash.

However, here's the solution – try to access 

This definitely looks like a bug in Max – it shouldn't crash.
However, here's the solution – try to access wind.title instead of name.

Max crashes when Patcher is closed and js holds a reference to it.