Fix unwanted moving part in element editor.

Fix an unwanted behavior when the properties dock widget is displayed :

1 there is no selection
2 the dock widget width is set to minimum
3 select a part, the dock widget gain new widgets used to edit the
current selected part and the width of the dock grow so the width of the
QGraphicsView is reduced and cause a mouse move event.
When this case occur the part is moved but they should not.

sources/editor/graphicspart/customelementgraphicpart.cpp

@@ -1308,14 +1308,29 @@ void CustomElementGraphicPart::hoverLeaveEvent(QGraphicsSceneHoverEvent *event)
 
 void CustomElementGraphicPart::mousePressEvent(QGraphicsSceneMouseEvent *event)
 {
-	if(event->button() == Qt::LeftButton)
+	if(event->button() == Qt::LeftButton) {
 		m_origin_pos = this->pos();
+		m_first_move = true;
+	}
 
 	QGraphicsObject::mousePressEvent(event);
 }
 
 void CustomElementGraphicPart::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 {
+		//m_first_move is used to avoid an unwanted behavior
+		//when the properties dock widget is displayed :
+		//1 there is no selection
+		//2 the dock widget width is set to minimum
+		//3 select a part, the dock widget gain new widgets used to edit
+		//the current selected part and the width of the dock grow
+		//so the width of the QGraphicsView is reduced and cause a mouse move event.
+		//When this case occur the part is moved but they should not. This bool fix it.
+	if (Q_UNLIKELY(m_first_move)) {
+		m_first_move = false;
+		return;
+	}
+
 	if((event->buttons() & Qt::LeftButton) && (flags() & QGraphicsItem::ItemIsMovable))
 	{
 		QPointF pos = event->scenePos() + (m_origin_pos - event->buttonDownScenePos(Qt::LeftButton));

sources/editor/graphicspart/customelementgraphicpart.h

@@ -328,6 +328,7 @@ class CustomElementGraphicPart : public QGraphicsObject, public CustomElementPar
 		Color _color;
 		bool _antialiased;
 		QPointF m_origin_pos;
+		bool m_first_move;
 };
 
 typedef CustomElementGraphicPart CEGP;