Consider the following code: KConfigGui::setSessionConfig(QStringLiteral("myApp"), QStringLiteral("myApp")); if (KMainWindow::canBeRestored(1)) { // do a bunch of stuff } KMainWindow::canBeRestored(1) will return true even though the newly-created session config is empty. This is because internally, it's doing this: const int n = group.readEntry("NumberOfWindows", 1); return number >= 1 && number <= n; So NumberOfWindows is not set, which causes it to fall back to 1. And then the function returns true because the number 1 satisfies both criteria. This can be trivially fixed by changing the default value of the readEntry() call from 1 to 0, and that's what I did in https://invent.kde.org/frameworks/kxmlgui/-/merge_requests/. However this so breaks Dolphin's manual session restore feature (which accidentally takes advantage of this bug to function) and I had to revert it. This bug report tracks this issue so that the fix can be merged after Dolphin and potentially other apps are fixed, or KF6--whichever comes first.
Could we just fix that?
Kate uses // restore all windows ;) for (int n = 1; KMainWindow::canBeRestored(n); n++) { newMainWindow(sessionConfig, QString::number(n)); } too, that is not good if this always does like there is win 1.
A possibly relevant merge request was started @ https://invent.kde.org/frameworks/kxmlgui/-/merge_requests/269
Git commit 8c9fb02a1d37672b26a03a9dd9e8675743deb269 by Christoph Cullmann. Committed on 09/03/2025 at 19:35. Pushed by cullmann into branch 'master'. ensure KMainWindow::canBeRestored is working with no data old behavior did always pretend there is data for window 1 M +2 -4 src/kmainwindow.cpp https://invent.kde.org/frameworks/kxmlgui/-/commit/8c9fb02a1d37672b26a03a9dd9e8675743deb269