Make whole menu item area clickable?

My menu buttons have a really annoying behaviour - if you hover over any part of the menu item, the style changes according to the 'hover' parameters - suggesting that the button is now clickable, BUT it is only actually clickable overt the text area ( where it gives me the finger!) - but not at the edges.
 
Is there any way to fix that? It is really confusing to  the user to click on a highlighted button and have nothing happen.
 
Thanks
 
Bill
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