Bug 371568

Hm, that's "interesting"... The window geometry restoration code is ancient, probably dates back to Qt 1.x and is shared with all the calligra applications. I'm not even sure I really understand what it's trying to do.

Um, actually, isn't this a Qt bug then? I know of no KDE or Qt application that uses showMaximized() directly, and the Qt documentation says to use 

http://doc.qt.io/qt-5/qwidget.html#saveGeometry

and 

http://doc.qt.io/qt-5/qwidget.html#restoreGeometry

Which is what we do:

void KisMainWindow::closeEvent(QCloseEvent *e)
{
...
    cfg.writeEntry("ko_windowstate", saveState().toBase64());
...
}

and

void KisMainWindow::initializeGeometry()
{
    // if the user didn's specify the geometry on the command line (does anyone do that still?),
    // we first figure out some good default size and restore the x,y position. See bug 285804Z.
    KConfigGroup cfg( KSharedConfig::openConfig(), "MainWindow");
    QByteArray geom = QByteArray::fromBase64(cfg.readEntry("ko_geometry", QByteArray()));
    if (!restoreGeometry(geom)) {
...
}

> Um, actually, isn't this a Qt bug then?

I'm not excluding the possibility that it's a Qt bug.

> I know of no KDE or Qt application that uses showMaximized() directly

It's a hardly used feature that applications request to open maximized directly.

> void KisMainWindow::initializeGeometry()

Can you point me to the code for that, then I can go through what it does.

Sure, that's here:

 https://phabricator.kde.org/diffusion/KRITA/browse/master/libs/ui/KisMainWindow.cpp;fbb623ff37d1225c0302d1ddb459a433bc555148$2388

Ok, found the problematic code:
void KisMainWindow::showEvent(QShowEvent *e)
{
    KXmlGuiWindow::showEvent(e);

    if (!d->geometryInitialized) {
        /**
         * We should move the window only *after* it has been shown on
         * screen, otherwise it will become owned by a wrong screen, which
         * will make positioning of all the child widgets wrong.
         * (see bug https://bugs.kde.org/show_bug.cgi?id=362025)
         *
         * This is actually a bug/feature of Qt 5.5.x and it has been
         * fixed in Qt 5.6.0. So we can avoid this delay on newer versions
         * of Qt.
         */
        QTimer::singleShot(1, this, SLOT(initializeGeometry()));
        d->geometryInitialized = true;
    }
}

Thus we have a show (normal geometry) with the initializeGeometry later. Which is exactly what I observe in KWin.

Ah, right! Well, since Qt 5.6 is now the version used for all our releases and the version on most distributions, I guess we can remove this again. I'll also propose raising the minimum version of Qt, but that might run into some resistance.

Git commit 3b62983593fbf5c293e603a2b2c92c83d70acc57 by Boudewijn Rempt.
Committed on 25/10/2016 at 07:23.
Pushed by rempt into branch 'master'.

Make Qt 5.6.0 the minimum with an override

Qt 5.6 has fixed the bug for which this reverted commit was
a hacky fix; the hacky fix caused problems for kwin because
we first show, then position the main window.

Revert "Fix wrong positioning of children/popup widgets"

This reverts commit ceff0e241bbd1c14b4b5ee5de11743b92fb7d760.

M  +3    -3    CMakeLists.txt
M  +2    -1    libs/ui/KisApplication.cpp
M  +1    -21   libs/ui/KisMainWindow.cpp
M  +0    -1    libs/ui/KisMainWindow.h

http://commits.kde.org/krita/3b62983593fbf5c293e603a2b2c92c83d70acc57