Hi, short use case for this problem: - open multiple windows with a few tabs each in Firefox, make sure the Firefox is setup to restore the session - close Firefox - logout - login - open Firefox again The problem: the ordering of restored Firefox windows is randomized in the task manager (although their position on the screen is preserved) Preferred behavior: the ordering of restored windows in the task manager to be in the order they were previous to closing This was lately working with no problems, even with dozens of windows open containing hundreds of tabs. It was an intermittent problem observed in previous 5.x versions of Plasma but seemed to have gotten fixed lately. However, with latest Plasma (5.13.2, and possibly 5.13.1 too) it appeared again, so I guess it is some kind of a regression. I have previously observed the same problem with Chromium, so I'm not sure if it has anything to do with GTK-based applications. For completeness sake, this also seemed to coincide with the update to Firefox 61 (or perhaps to one of the latest revisions of Firefox 60) if that is of any help.
There's no code present to remember or restore any positions. If sorting is set to e.g. alphabetic (the default) it's, well, alphabetic. If it's set to Manual, new windows are appended in the order they are opened. So it's up to the application to reopen its windows in the right order.