Not a big deal today, anyway I am happy to share the solution for systray dragging issue which is a little annoyance for years. The problem is, the systray module behaves oddly in compare with other modules on the shelf. You can not move it on the shelf to the target position. Just use other modules as "glue".
During the module code studying I realized there does exists the gadget container (gadcon) which is common for every well coded gadget with possibility of its manipulation. Then I found the problem. Gadcon is masked with X rectangle used for displaying apps icons. So, my goal was just to reveal the part of gadcon.
This is the picture for better imagination
Now we can treat it as other gadgets after clicking the 5 pixels high space above the icons. The systray module needs a lot of care but I hope this mini fix will help a little bit.