# Objective
Fixes two issues related to #13208.
First, we ensure render resources for a window are always dropped first
to ensure that the `winit::Window` always drops on the main thread when
it is removed from `WinitWindows`. Previously, changes in #12978 caused
the window to drop in the render world, causing issues.
We accomplish this by delaying despawning the window by a frame by
inserting a marker component `ClosingWindow` that indicates the window
has been requested to close and is in the process of closing. The render
world now responds to the equivalent `WindowClosing` event rather than
`WindowCloseed` which now fires after the render resources are
guarunteed to be cleaned up.
Secondly, fixing the above caused (revealed?) that additional events
were being delivered to the the event loop handler after exit had
already been requested: in my testing `RedrawRequested` and
`LoopExiting`. This caused errors to be reported try to send an exit
event on the close channel. There are two options here:
- Guard the handler so no additional events are delivered once the app
is exiting. I ~considered this but worried it might be confusing or bug
prone if in the future someone wants to handle `LoopExiting` or some
other event to clean-up while exiting.~ We are now taking this approach.
- Only send an exit signal if we are not already exiting. ~It doesn't
appear to cause any problems to handle the extra events so this seems
safer.~
Fixing this also appears to have fixed#13231.
Fixes#10260.
## Testing
Tested on mac only.
---
## Changelog
### Added
- A `WindowClosing` event has been added that indicates the window will
be despawned on the next frame.
### Changed
- Windows now close a frame after their exit has been requested.
## Migration Guide
- Ensure custom exit logic does not rely on the app exiting the same
frame as a window is closed.
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