doc: Add note about platform support for window positions

On some platforms, such as Wayland (and also eglfs), manual window positioning is not supported. Since this has caused confusion in the past, we add a note to the documentation. Pick-to: 6.2 6.5 Fixes: QTBUG-86780 Change-Id: Idf8dcdfad8ccfb9eb0f704fce05216562e433e20 Reviewed-by: Tor Arne Vestbø <[email protected]>
leadtobetter · Mar 17, 2023 · 5c7a3ea · 5c7a3ea
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diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
@@ -1882,6 +1882,10 @@ void QWindow::setFramePosition(const QPoint &point)
     For interactively moving windows, see startSystemMove(). For interactively
     resizing windows, see startSystemResize().
 
+    \note Not all windowing systems support setting or querying top level window positions.
+    On such a system, programmatically moving windows may not have any effect, and artificial
+    values may be returned for the current positions, such as \c QPoint(0, 0).
+
     \sa position(), startSystemMove()
 */
 void QWindow::setPosition(const QPoint &pt)
@@ -1905,6 +1909,10 @@ void QWindow::setPosition(int posx, int posy)
     \fn QPoint QWindow::position() const
     \brief Returns the position of the window on the desktop excluding any window frame
 
+    \note Not all windowing systems support setting or querying top level window positions.
+    On such a system, programmatically moving windows may not have any effect, and artificial
+    values may be returned for the current positions, such as \c QPoint(0, 0).
+
     \sa setPosition()
 */
 

diff --git a/src/widgets/doc/src/windows-and-dialogs/mainwindow.qdoc b/src/widgets/doc/src/windows-and-dialogs/mainwindow.qdoc
@@ -115,6 +115,15 @@
     depends on the result of QWidget::frameGeometry() and the
     capability of the window manager to do proper window placement,
     neither of which can be guaranteed.
+
+    \section2 Wayland Peculiarities
+
+    On Wayland, programmatically setting or getting the position of a top-level window from the
+    client-side is typically not supported. Technically speaking, it depends on the shell
+    interface. For typical desktop compositors, however, the default shell interface will be
+    \c{XDG Shell}, which does not support manual positioning of windows. In such cases, Qt will
+    ignore calls to set the top-level position of a window, and, when queried, the window position
+    will always be returned as QPoint(0, 0).
 */
 
 /*!

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
@@ -3547,6 +3547,10 @@ int QWidget::y() const
     See the \l{Window Geometry} documentation for an overview of geometry
     issues with windows.
 
+    \note Not all windowing systems support setting or querying top level window positions.
+    On such a system, programmatically moving windows may not have any effect, and artificial
+    values may be returned for the current positions, such as \c QPoint(0, 0).
+
     \sa frameGeometry, size, x(), y()
 */
 QPoint QWidget::pos() const