The tabs are now inserted just before the "+" tab instead of removing the "+" tab, adding the tab and then re-adding the "+" button.
However, sometimes tab's title won't show for an unknown reason, and it's impossible to remove the tab at the right of the "+" button (it will instantly create another one).
Also, show and hide function (that were in comment before) are removed. Because of the inheritance of the resultspanel from a Panel which contains show and hide functions, they were ambiguous and useless.