Fix MouseMove event handling when opening a new tab with middle click.

When opening a new tab by middle clicking on a link in a web page, two
MouseMove events are sent to Chromium consecutively, without getting
proper acknowledgment events, which causes further move events not
to be handled properly.
Fix consists in preventing the second move event from being sent.

Change-Id: Ia0a64698476226e472faa53f75b51dfb6ed477c9
Task-number: QTBUG-50031
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/webenginewidgets/api/qwebenginepage.cpp b/src/webenginewidgets/api/qwebenginepage.cpp
index bb8babd7a..61feec244 100644
--- a/src/webenginewidgets/api/qwebenginepage.cpp
+++ b/src/webenginewidgets/api/qwebenginepage.cpp
@@ -185,6 +185,7 @@ QWebEnginePagePrivate::QWebEnginePagePrivate(QWebEngineProfile *_profile)
     , view(0)
     , isLoading(false)
     , scriptCollection(new QWebEngineScriptCollectionPrivate(browserContextAdapter()->userScriptController(), adapter.data()))
+    , m_isBeingAdopted(false)
 {
     memset(actions, 0, sizeof(actions));
 }
@@ -298,7 +299,20 @@ void QWebEnginePagePrivate::adoptNewWindow(WebContentsAdapter *newWebContents, W
 {
     Q_Q(QWebEnginePage);
     Q_UNUSED(userGesture);
+
     QWebEnginePage *newPage = q->createWindow(toWindowType(disposition));
+
+    // Mark the new page as being in the process of being adopted, so that a second mouse move event
+    // sent by newWebContents->initialize() gets filtered in RenderWidgetHostViewQt::forwardEvent.
+    // The first mouse move event is being sent by q->createWindow(). This is necessary because
+    // Chromium does not get a mouse move acknowledgment message between the two events, and
+    // InputRouterImpl::ProcessMouseAck is not executed, thus all subsequent mouse move events
+    // get coalesced together, and don't get processed at all.
+    // The mouse move events are actually sent as a result of show() being called on
+    // RenderWidgetHostViewQtDelegateWidget, both when creating the window and when initialize is
+    // called.
+    newPage->d_func()->m_isBeingAdopted = true;
+
     // Overwrite the new page's WebContents with ours.
     if (newPage && newPage->d_func() != this) {
         newPage->d_func()->adapter = newWebContents;
@@ -306,6 +320,14 @@ void QWebEnginePagePrivate::adoptNewWindow(WebContentsAdapter *newWebContents, W
         if (!initialGeometry.isEmpty())
             emit newPage->geometryChangeRequested(initialGeometry);
     }
+
+    // Page has finished the adoption process.
+    newPage->d_func()->m_isBeingAdopted = false;
+}
+
+bool QWebEnginePagePrivate::isBeingAdopted()
+{
+    return m_isBeingAdopted;
 }
 
 void QWebEnginePagePrivate::close()