text.autoCopySelection does not work in some scenarios

text.autoCopySelection isn't working in linux_x86_64(manjaro KDE X11)
In wind, the middle mouse button works.
wind to the system clipboard or wind to other software (such as Notepad/browser) does not work. （paste）
在wind里，鼠标中键是工作的，wind到系统剪切板或wind到其他软件（如记事本 浏览器）是不工作的。

Start by reproducing text.autoCopySelection on Linux x86_64 with Manjaro KDE under X11, comparing middle-click behavior inside WindTerm with pasting into the system clipboard and another application. Done means copied text can be pasted externally in the reported scenario; the issue names no files or tests, so locating the implementation and suitable regression coverage is part of the investigation.

Written by the indexing model from the issue text.