I noticed that Chrome's window had the property
```
_KDE_NET_WM_DESKTOP_FILE(UTF8_STRING) = "org.kde.kdialog"
```
and it uses `kdialog --attach` for a Save As dialog with proper parent dimming
* Attached `kdialog` to another window, it never got its desktop file name forcefully changed to that.
* Verified apps own windows still get the property set