`ximagesrc` does not draw mouse cursor when window, catched with xname, is moved.

[CARUSO Julien]

Hello,

I am using `ximagesrc` to stream specific window using xname property, but I have some trouble with mouse cursor when windows position change.

I launch `xclock` and `gst-launch ximagesrc xname="xclock" ! ximagesink`
When xclock windows is moved then the mouse pointer is not well drawn, the offset corresponds to the movement of the window. If the xclock window is too far from its starting position, the cursor is no longer drawn.

Is this behavior normal ? 


 Screen 1                          Screen 2
+---------------------------------+---------------------------------+
| +---------+                     |                                 |
| |         |                     |         gst-launch              |
| |         |                     |         +---------+             |
| |         |                     |         |         |             |
| |    +---------+                |         |         |             |
| |    |    |    |                |         |         |             |
| +----|----+    |                |         |         |             |
|      |    X    |                |         |       X |             |
|      |         |                |         +---------+             |
|      |         |                |                                 |
|      +---------+                |                                 |
+---------------------------------+---------------------------------+
The X represent the mouse pointer: it is drawn with an offset.

Configuration:
* Debian 9/11
* Gstreamer 1.16/1.20
* XFCE
* Dual-screen


Regards,

--
Julien