This event is generated any time the user moves the cursor to a grid control cell using the mouse. This event is similar to MSG-GOTO-CELL, which generates a message when the cursor is moved via the keyboard. One reason you may want to know whether the user is moving to the cell via the mouse or the keyboard is if you are preventing the user from visiting a particular cell. You may want to leave the cursor in its original location if the user clicks on the cell with the mouse. But if the user types a key, you may want to skip over the field (you can tell which direction to skip by looking at the cell the user is starting from). This event differs from MSG-GOTO-CELL in that a message is generated by MSG-GOTO-CELL-MOUSE even when the user clicks in the grid control cell that contains the cursor.
For details about the handling of this event, see MSG-GOTO-CELL.