Cancel any edit in progress when wxTreeCtrl is scrolled

Otherwise the editor could be scrolled out of view, confusing the user.

Closes https://github.com/wxWidgets/wxWidgets/pull/1522

src/qt/treectrl.cpp

@@ -23,6 +23,7 @@
 
 #include <QtWidgets/QTreeWidget>
 #include <QtWidgets/QHeaderView>
+#include <QtWidgets/QScrollBar>
 #include <QtGui/QPainter>
 
 namespace
@@ -142,6 +143,8 @@ public:
                 this, &wxQTreeWidget::OnItemCollapsed);
         connect(this, &QTreeWidget::itemExpanded,
                 this, &wxQTreeWidget::OnItemExpanded);
+        connect(verticalScrollBar(), &QScrollBar::valueChanged,
+                this, &wxQTreeWidget::OnTreeScrolled);
 
         setItemDelegate(&m_item_delegate);
         setDragEnabled(true);
@@ -438,6 +441,12 @@ private:
         EmitEvent(expandedEvent);
     }
 
+    void OnTreeScrolled(int)
+    {
+        if ( GetEditControl() != NULL )
+            closeEditor(GetEditControl()->GetHandle(), QAbstractItemDelegate::RevertModelCache);
+    }
+
     void tryStartDrag(const QMouseEvent *event)
     {
         wxEventType command = event->buttons() & Qt::RightButton