Several changes:

 - added WFileDropWidget with example
 - avoid XSS when using WString::tr with user-supplied arg
 - WDropEvent: mouseEvent() and touchEvent() return pointers and make defensive copy, breaks backwards compatibility
 - WObject should not be copy assignable
 - Fixing compiler warnings
 - Fixes to touch selection behaviour in WTableView and WTreeView (issue #4656)
 - Fixed PayPal regression caused by HTTP client only using TLSv1, not later versions
 - Use $.event.fix on events triggered. This fixes click events and mousedown events on WTableViews when more recent versions of jQuery are used.
 - Fixed regression with touch for WCartesianChart since touchEvents were implemented
 - Workaround in JSON tests for boost versions before 1.47
 - Only sync back WJavaScriptExposableObjects if they've been changed (fixes issue #5414)
 - Fix issue #5404: stuck WPopupMenu button
 - Added option for specifying crosshair color, resolves issue #5180
 - fix WTreeView error while handling row removals: error in WTreeView::widgetForIndex()
 - Added Combined session tracking mode
 - Removed redirectToSession()
 - Added missing include that made MinGW build fail

Author: RockinRoel

examples/CMakeLists.txt

@@ -221,6 +221,7 @@ SUBDIRS(
   dragdrop
   feature
   filetreetable
+  filedrop
   form
   gitmodel
   hangman

examples/filedrop/CMakeLists.txt

@@ -0,0 +1,18 @@
+#
+# The ADD_EXAMPLE macro (defined in examples/CMakeLists.txt) ensures that
+# the example is correctly built for the requested connector. It is equivalent
+# to the following two lines:
+#   ADD_EXECUTABLE(hello.wt hello.C)
+#   TARGET_LINK_LIBRARIES(hello.wt ${EXAMPLES_CONNECTOR})
+# except when the ISAPI (for Microsoft IIS) connector is used, where it will
+# build a DLL with the proper symbols exported.
+#
+WT_ADD_EXAMPLE(filedrop.wt filedrop.C FileDropApplication.C)
+
+#
+# If you have Wt installed somehwere, you should use the
+# installed Wt header files for your own Wt projects.
+# e.g. INCLUDE_DIRECTORIES(/usr/local/include)
+# instead of the following:
+#
+INCLUDE_DIRECTORIES(${WT_SOURCE_DIR}/src)

examples/filedrop/FileDropApplication.C

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2016 Emweb bvba, Herent, Belgium.
+ *
+ * See the LICENSE file for terms of use.
+ */
+
+#include "FileDropApplication.h"
+
+#include <Wt/WContainerWidget>
+#include <Wt/WText>
+#include <Wt/WFileDropWidget>
+#include <Wt/WFileUpload>
+
+#include <iostream>
+#include <fstream>
+
+using namespace Wt;
+
+static const std::string UPLOAD_FOLDER = "./uploaded/";
+
+FileDropApplication::FileDropApplication(const WEnvironment& env)
+  : WApplication(env)
+{
+  setTitle("File Drop Example");
+
+  new WText("<h1>Try dropping a file in the widget below</h1>", root());
+  
+  drop_ = new WFileDropWidget();
+  root()->addWidget(drop_);
+
+  connectFileUpload();
+  
+  log_ = new WText(root());
+}
+
+void FileDropApplication::connectFileUpload()
+{
+  drop_->fileUpload()->setMultiple(true);
+  drop_->fileUpload()->uploaded().connect(this, &FileDropApplication::saveFile);
+  drop_->fileUpload()->fileTooLarge().connect(this,
+					      &FileDropApplication::fileTooBig);
+}
+
+void FileDropApplication::saveFile()
+{
+  std::vector<Http::UploadedFile> files = drop_->fileUpload()->uploadedFiles();
+  for (int i =0; i < files.size(); i++) {
+    std::string spool = files[i].spoolFileName();
+    
+    std::ifstream src(spool.c_str(), std::ios::binary);
+    std::ofstream dest((UPLOAD_FOLDER + files[i].clientFileName()).c_str(),
+		       std::ios::binary);
+    if (dest.fail()) {
+      std::cerr << "**** ERROR: The output file could not be opened"
+		<< std::endl;
+      break;
+    }
+    
+    dest << src.rdbuf();
+
+    // Add a little block to the container-widget
+    WContainerWidget *block = new WContainerWidget(drop_);
+    block->setWidth(20);
+    block->setHeight(20);
+    block->setMargin(10);
+    block->decorationStyle().setBackgroundColor(WColor("black"));
+  }
+
+  
+  log_->setText("Thanks for the file(s)");
+  
+  drop_->resetUpload();
+  connectFileUpload();
+}
+
+void FileDropApplication::fileTooBig()
+{
+  log_->setText("The file is too big ...");
+}

examples/filedrop/FileDropApplication.h

@@ -0,0 +1,34 @@
+// This may look like C code, but it's really -*- C++ -*-
+/*
+ * Copyright (C) 2016 Emweb bvba, Herent, Belgium.
+ *
+ * See the LICENSE file for terms of use.
+ */
+
+#ifndef FILEDROPAPPLICATION_H_
+#define FILEDROPAPPLICATION_H_
+
+#include <Wt/WApplication>
+
+using namespace Wt;
+
+namespace Wt {
+  class WFileDropWidget;
+}
+
+class FileDropApplication : public WApplication
+{
+public:
+  FileDropApplication(const WEnvironment& env);
+
+private:
+  WText *log_;
+  WFileDropWidget *drop_;
+
+  void saveFile();
+  void fileTooBig();
+  void connectFileUpload();
+};
+
+
+#endif

examples/filedrop/filedrop.C

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2016 Emweb bvba, Herent, Belgium.
+ *
+ * See the LICENSE file for terms of use.
+ */
+#include "FileDropApplication.h"
+
+using namespace Wt;
+
+WApplication *createApplication(const WEnvironment& env)
+{
+  return new FileDropApplication(env);
+}
+
+int main(int argc, char **argv)
+{
+  return WRun(argc, argv, &createApplication);
+}
+

examples/filedrop/uploaded/README

@@ -0,0 +1,2 @@
+==== README file mainly to commit empty folder to git
+This folder contains all files uploaded through the filedrop widget