Control lock

XOJO 2019r3 / Windows 10

I just saw that a control that has been locked still can be moved with the cursor keys on the keyboard.
Trying to move it with the mouse is blocked as should be.
Is this a bug ? Am I missing a setting ? Do I something wrong ?

Selecting a control in the left navigator pane, directly put it into ‘blue’ selected, and so the control can not be moved with the arrow keys. Using the keyboard arrows the controls selection is changing.
In XOJO 2018r4 selecting a control in the navigator it became light grey and could then be moved with the arrow keys of the keyboard.
If you select the control on the screen then the arrow keys can move it. But it is not always possible to select the control on the screen : for example a control behind another control can not be selected with the mouse.
Bug ?