Fix keyboard focus after dropping parts from floating docks

Dragging a part from a floating Parts window can leave that window active after the drop. Setting focus on the model view alone does not activate its window, so movement shortcuts remain in the Parts list until the model is clicked.

Activate the receiving window before focusing the view after accepted part or color drops so keyboard commands can reach the model immediately.

Fixes #1040.

common/lc_viewwidget.cpp

@@ -370,6 +370,7 @@ void lcViewWidget::dropEvent(QDropEvent* DropEvent)
 	if (MimeData->hasFormat("application/vnd.leocad-part") || MimeData->hasFormat("application/vnd.leocad-color"))
 	{
 		mView->EndDrag(true);
+		window()->activateWindow();
 		setFocus(Qt::MouseFocusReason);
 
 		DropEvent->accept();