What do you mean by "ïf the control is selected"?
I remember a bugreport wehere something similar happend if the object's width or height was selected in Object Inspector.
Bart
I post a photo just before, you may have a look
more details:
when the panel not selected, then press the left button and drag it to somewhere else, is all ok
then release button, the panel remain selected, it has 8 dot around the boundary
press down button again and drag it to somewhere, the panel will have a random *jump*, the related offset of cursor and panel is changed, even the cursor may out of the panel.
it's hard to take a screenshot, so I take a photo,
firstly I think may be my mouse fail, but compare side by side, the 1.2.6 is good.