The mouse position should be relative to the Edit field, in other words probably [4,11] in this case. The Edit field is at [50,10] and [54,11] is the position within the form.
This is probably also wrong for other Mouse events that report the mouse position.
Run DemoMultiEdit. Click in the top left corner. Notice:
{"EventName":"MouseUp","ID":"F1.NotePad","Info":[54,11,0,0]}
The mouse position should be relative to the Edit field, in other words probably [4,11] in this case. The Edit field is at [50,10] and [54,11] is the position within the form.
This is probably also wrong for other Mouse events that report the mouse position.