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

Due to a Qt issue on Linux, disable drag/drop on the scenes/sources list
on Linux for the time being.

UI/window-basic-main.cpp

@@ -233,6 +233,11 @@ 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();