QmlDesigner: adding a distinguished context for the form editor

Since Actions like copy/paste and delete interfiere
with controls like LineEdit, I added a special context
for the form editor. Now copy/paste/delete on the Qml items
are only registered for the form editor context and copying the contens
of a LineEdit will not lead to copy an item instead, anymore.

Reviewed-by: Kai Koehne

src/plugins/qmldesigner/designmodewidget.cpp

@@ -30,6 +30,7 @@
 #include "designmodewidget.h"
 #include "qmldesignerconstants.h"
 #include "styledoutputpaneplaceholder.h"
+#include "designmodecontext.h"
 
 #include <model.h>
 #include <rewriterview.h>
@@ -685,6 +686,9 @@ void DesignModeWidget::setup()
         //### we now own these here
         rightLayout->addWidget(m_statesEditorWidget.data());
 
+        FormEditorContext *context = new FormEditorContext(m_formEditorView->widget());
+        Core::ICore::instance()->addContextObject(context);
+
         // editor and output panes
         m_outputPlaceholderSplitter->addWidget(m_formEditorView->widget());
         m_outputPlaceholderSplitter->addWidget(m_outputPanePlaceholder);