Keep paste at original XML position instead of moving to cursor

Commit dd0c194a3 (#913) moved the pasted group to the cursor position
at construction time. The desired behaviour is that items appear at
their original XML coordinates (where they were copied from) so the
user starts from the origin. The grid-snapped movement baseline and
the context-menu restoration from that commit are kept.

sources/diagramevent/diagrameventaddpaste.cpp

@@ -40,6 +40,7 @@
 	DiagramEventAddPaste::DiagramEventAddPaste(Diagram *diagram, const QPointF &start_pos) :
 	DiagramEventInterface(diagram)
 {
+	Q_UNUSED(start_pos);  // items stay at their original XML position
 		//DiagramEventInterface::init() is called by Diagram::setEventInterface
 		//only when it is replacing an earlier interface, so call it here as
 		//DiagramEventAddMacro does.
@@ -85,33 +86,23 @@
 	};
 	const QPointF grid_origin = snapGrid(top_left);
 
-		//Move the group to the cursor, rather than the cursor to the
-		//group. Both put the copy under the pointer, but warping the
-		//pointer also drags it back to the original's position, so the
-		//copy appears exactly on top of what was copied until the mouse
-		//is moved -- which is the thing pasting under the cursor was
-		//meant to avoid (issue #913). Taking the pointer away from
-		//where the user put it is also its own surprise.
-	m_group_origin = snapGrid(start_pos);
-	const QPointF offset = m_group_origin - grid_origin;
-
-		//Store each item's position after the move. moveTo() applies a
+		//Store each item's original position.  moveTo() applies a
 		//grid-snapped delta from the baseline to these, so items
 		//preserve their layout and move in whole grid steps.
 	for (auto *item : movable) {
-		item->setPos(item->pos() + offset);
 		m_relative_pos.insert(item, item->pos());
 	}
+	m_group_origin = grid_origin;
 
-		//The conductors were laid out against the old terminal
+		//The conductors were laid out against the original terminal
 		//positions, so re-route them before anything is drawn.
 	const QList<Conductor *> conductors = m_content.conductors(DiagramContent::AnyConductor);
 	for (auto *conductor : conductors) {
 		conductor->updatePath();
 	}
 
-		//The baseline is known now, so moveTo() does not have to
-		//capture one from the first mouse movement.
+		//The baseline is the group's grid-snapped origin, so moveTo()
+		//does not have to capture one from the first mouse movement.
 	m_initial_cursor = m_group_origin;
 	m_baseline_captured = true;