That works fine for getting the focus in the widget when the cursor enters the widget. The problem is knowing when the cursor has left the widget if it does not go into another widget which has this bind. The problem is made more difficult since there are a number widgets with this bind but only a certain number should be recognised at a specific time. Then later on another set of widgets should be recognised. This was why I was trying to find a way to use the focusFollowsMouse which would let me detect the cursor had left a widget and then disable this function until an Entry widget had been 'entered'.
I know there also is a Leave function which detects when the mouse has left a widget. An alternate would be to use this but then I do not know how to take away the Focus from a widget without another widget having the focus.