Klaus:
I found the solution by myself, using the following variable:
fillcolorhover
I use the following code to achieve a superposition of a yellow area without border on the hotspot, as the cursor moves over it.
visible="true"
borderwidth="0.0" borderwidthhover="0.0"
borderalpha="0.0" borderalphahover="0.0"
fillalpha="0.0" fillalphahover="0.2"
fillcolorhover="0xFFCC00"
Thanks anyway
Best regards
Fernando