Enhance Windows Stability

[rustbasic]

Dear emilk,

Programs built with egui on Windows are terminating every hour on average.
When this commit is applied, it works fine for about 6 hours on average.

I've been testing it for over 6 months and have submitted multiple PRs since 6 months ago,
but they haven't applied it yet.

Thank you.

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/5723-patch160
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

[lucasmerlin]

Can you explain why this change makes a difference? And what was changed for which reason? I tried to understand it from the diff but I can't make sense of it.

[rustbasic]

Can you explain why this change makes a difference? And what was changed for which reason? I tried to understand it from the diff but I can't make sense of it.

In Windows, the run_ui_and_paint() function is called when it's EventResult::Wait.
Previously, the return value of the run_ui_and_paint() function was ignored.
This is a modification to apply the return value of the run_ui_and_paint() function.