Lock the window's caption area vertically inside its screen

The current code that locks the window does not take into account
screens that don't start at non-zero y coordinate, nor does it cap the
bottom of the window.

Task-number: QTBUG-106031
Pick-to: 6.4
Change-Id: Ic22c016d32dca9d288a2a56c51ccde78144b436e
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/wasm/qwasmwindow.cpp

@@ -134,20 +134,25 @@ QWasmScreen *QWasmWindow::platformScreen() const
 
 void QWasmWindow::setGeometry(const QRect &rect)
 {
-    QRect r = rect;
+    const QRect clientAreaRect = ([this, &rect]() {
-    if (m_needsCompositor) {
+        if (!m_needsCompositor)
-        int yMin = window()->geometry().top() - window()->frameGeometry().top();
+            return rect;
 
-        if (r.y() < yMin)
+        const int captionHeight = window()->geometry().top() - window()->frameGeometry().top();
-            r.moveTop(yMin);
+        const auto screenGeometry = screen()->geometry();
-    }
+
+        QRect result(rect);
+        result.moveTop(std::max(std::min(rect.y(), screenGeometry.bottom()),
+                                screenGeometry.y() + captionHeight));
+        return result;
+    })();
     bool shouldInvalidate = true;
     if (!m_windowState.testFlag(Qt::WindowFullScreen)
         && !m_windowState.testFlag(Qt::WindowMaximized)) {
-        shouldInvalidate = m_normalGeometry.size() != r.size();
+        shouldInvalidate = m_normalGeometry.size() != clientAreaRect.size();
-        m_normalGeometry = r;
+        m_normalGeometry = clientAreaRect;
     }
-    QWindowSystemInterface::handleGeometryChange(window(), r);
+    QWindowSystemInterface::handleGeometryChange(window(), clientAreaRect);
     if (shouldInvalidate)
         invalidate();
     else