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    <head>
      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Infinite loop when processing mouse events synchronously"
   href="https://bugs.webkit.org/show_bug.cgi?id=153995">153995</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Infinite loop when processing mouse events synchronously
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Local Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>WebKit2
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>cgarcia&#64;igalia.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>andersca&#64;apple.com, darin&#64;apple.com, sam&#64;webkit.org
          </td>
        </tr>

        <tr>
          <th>Blocks</th>
          <td>153740
          </td>
        </tr></table>
      <p>
        <div>
        <pre>This happened with WTR in the GTK+ port after landing patch in <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED - [GTK] WebKitWebView should send crossing events to the WebProcess"
   href="show_bug.cgi?id=153740">bug #153740</a>. The thing is that WTR forces events handling IPC messages to be synchronous. When a drag and drop operation is in progress, the web process ignores mouse move events and replies with DidReceiveEvent signal. The DidReceiveEvent message handler in WebPageProxy checks if we have a m_nextMouseMoveEvent and handles it, but when all this happens synchronously the m_nextMouseMoveEvent is the current one because we haven't returned yet from handleMouseEvent(). We need to invalidate the m_nextMouseMoveEvent before calling handleMouseEvent().

#0  0x00007ffff5bbb133 in IPC::Connection::sendMessage(std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, unsigned int, bool) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#1  0x00007ffff5bbc48c in IPC::Connection::sendSyncMessage(unsigned long, std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, std::chrono::duration&lt;long, std::ratio&lt;1l, 1000l&gt; &gt;, unsigned int) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#2  0x00007ffff5bbb1f5 in IPC::Connection::sendMessage(std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, unsigned int, bool) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#3  0x00007ffff5c20e37 in WebKit::ChildProcessProxy::sendMessage(std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, unsigned int) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#4  0x00007ffff5c5c02a in bool WebKit::ChildProcessProxy::send&lt;Messages::WebPage::MouseEvent&gt;(Messages::WebPage::MouseEvent&amp;&amp;, unsigned long, unsigned int) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#5  0x00007ffff5c4579c in WebKit::WebPageProxy::handleMouseEvent(WebKit::NativeWebMouseEvent const&amp;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#6  0x00007ffff5c5170a in WebKit::WebPageProxy::didReceiveEvent(unsigned int, bool) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#7  0x00007ffff5e686f7 in WebKit::WebPageProxy::didReceiveMessage(IPC::Connection&amp;, IPC::MessageDecoder&amp;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#8  0x00007ffff5bbf039 in IPC::MessageReceiverMap::dispatchMessage(IPC::Connection&amp;, IPC::MessageDecoder&amp;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#9  0x00007ffff5c75102 in WebKit::WebProcessProxy::didReceiveMessage(IPC::Connection&amp;, IPC::MessageDecoder&amp;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#10 0x00007ffff5bbb546 in IPC::Connection::dispatchMessage(std::unique_ptr&lt;IPC::MessageDecoder, std::default_delete&lt;IPC::MessageDecoder&gt; &gt;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#11 0x00007ffff5bbb89e in IPC::Connection::SyncMessageState::dispatchMessages(IPC::Connection*) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#12 0x00007ffff5bbb4a1 in IPC::Connection::dispatchSyncMessage(IPC::MessageDecoder&amp;) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#13 0x00007ffff5bbb5bd in IPC::Connection::dispatchMessage(std::unique_ptr&lt;IPC::MessageDecoder, std::default_delete&lt;IPC::MessageDecoder&gt; &gt;) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#14 0x00007ffff5bbb89e in IPC::Connection::SyncMessageState::dispatchMessages(IPC::Connection*) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#15 0x00007ffff5bbbd8f in IPC::Connection::waitForSyncReply(unsigned long, std::chrono::duration&lt;long, std::ratio&lt;1l, 1000l&gt; &gt;, unsigned int) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#16 0x00007ffff5bbc4b8 in IPC::Connection::sendSyncMessage(unsigned long, std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, std::chrono::duration&lt;long, std::ratio&lt;1l, 1000l&gt; &gt;, unsigned int) () from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#17 0x00007ffff5bbb1f5 in IPC::Connection::sendMessage(std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, unsigned int, bool) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
#18 0x00007ffff5c20e37 in WebKit::ChildProcessProxy::sendMessage(std::unique_ptr&lt;IPC::MessageEncoder, std::default_delete&lt;IPC::MessageEncoder&gt; &gt;, unsigned int) ()
   from /home/cgarcia/src/git/gnome/WebKit/WebKitBuild/Release/lib/libwebkit2gtk-4.0.so.37
......</pre>
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