MAME emulator. When pressing the arrow keys, the cursor (cell highlight) seems to try to move in the indicated direction but very often snaps back to the mouse cursor. At the same time, the mouse cursor also moves pixel-by-pixel in the indicated direction.
I guess that is because the mouse settings might be too sensible. Anyhow I uploaded a new version which changes the field only if the mouse cursor entered a new field or if the mouse button has been pressed. Probably this mitigates the issue.
That the mouse follows the cursor keys is mame specific. There is a setting that the mouse follows the cursor keys (INC/DEC). You can disable it: press TAB, "Input Settings", "Input Assignments (this system)". Scroll down to "Mouse X Analog Inc". There is the key (Right) defined which moves the mouse by one. Press delete to undefine the key. Do the same for X Dec and Y Inc/Dec. Close the settings with TAB.
You might experience that the TAB key is not working, then on Windows you need to press Scroll-Lock before (on Mac FN+Delete/Backspace).