why does lock screen doesn't locks the screen?

[Tiemo Hollmann TB]

Hello,

In a function I set the screenMouseLoc to four different locations on an
image to get the mousecolor of these four locations.

I have set the screen lock at the beginning of the function, but the cursor
is flickering at all four locations, so obviously the screen is redrawn
everytime I set the mouse at a new location  though the screenloc is true.

What can I do to not see the mouse (and perhaps speed up the function), and
why does the lock screen doesn't work in this case?

Thanks

Tiemo