Revert "UI: Disable drag/drop on Linux scenes/sources (for now)"

This reverts commit 457adcedd319ca2317d7cd5300694d486e88af90.

Requires https://github.com/obsproject/obs-browser/pull/304

UI/source-tree.cpp

@@ -883,11 +883,8 @@ Qt::ItemFlags SourceTreeModel::flags(const QModelIndex &index) const
 	obs_sceneitem_t *item = items[index.row()];
 	bool is_group = obs_sceneitem_is_group(item);
 
-	/* XXX: Disable drag/drop on Linux until Qt issues are fixed */
 	return QAbstractListModel::flags(index) | Qt::ItemIsEditable |
-#if defined(_WIN32) || defined(__APPLE__)
 	       Qt::ItemIsDragEnabled |
-#endif
 	       (is_group ? Qt::ItemIsDropEnabled : Qt::NoItemFlags);
 }
 

UI/window-basic-main.cpp

@@ -233,11 +233,6 @@ OBSBasic::OBSBasic(QWidget *parent)
 	ui->previewDisabledWidget->setVisible(false);
 	ui->contextContainer->setStyle(new OBSProxyStyle);
 
-	/* XXX: Disable drag/drop on Linux until Qt issues are fixed */
-#if !defined(_WIN32) && !defined(__APPLE__)
-	ui->scenes->setDragDropMode(QAbstractItemView::NoDragDrop);
-#endif
-
 	startingDockLayout = saveState();
 
 	statsDock = new OBSDock();