# Objective

Closes #61054

This PR fixes Zed window not repainting after they are uncovered on X11.
When an X11 window becomes visible after being covered, X11 sends an
`Expose` event to tell the application that the window contents need to
be presented again. Previously, Zed stored this event and waited for the
periodic refresh loop to request a presentation but, the refresh loop is
stopped while a window is fully hidden to avoid unnecessary rendering.
This meant there might be no refresh tick to handle the pending
exposure.

window is fully hidden -> periodic refresh loop stops

window is uncovered -> expose event -> waits for refresh loop -> window
may remain blank

This change requests one presentation directly after processing the
pending X11 events. Multiple `Expose` events for the same window are
coalesced, and unmapped windows are ignored.

## Solution

window is uncovered -> expose event -> presentation is requested ->
window contents are displayed

Required presentations are also excluded from inactive-window frame
throttling, so the request is not dropped when Zed is unfocused. Regular
rendering for unfocused or fully obscured windows remains throttled.

## Testing
Check the issue being closed on steps to reproduction.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable


Release Notes:

- Fixed Zed windows sometimes not repainting after being uncovered on
X11