There used to be a little patch you needed to add to get the '+' key to work as the zoom key on a laptop. It had to do with the lack of a numeric keypad. Then the main CVS got fixed and I lost my notes.
However, recently on my Toshiba laptop running RedHat 7.3, the + key no longer wants to zoom... and 'search' turns up none of the references. [probably in the old forum archives]
The '-' still zooms out, but the '+' does not zoom in.
Sakshale