Fix eventful trying to show sidebar

It should not try to do that if e.g. showing buildingitems. Maybe later we will have more valid focus strings (e.g. custom item view for some buildings) but for now just use vanilla (or callback function not a class)

plugins/lua/eventful.lua

@@ -110,8 +110,6 @@ function registerSidebar(shop_name,callback)
                 local sidebar=callback{workshop=wshop}
                 if string.sub(dfhack.gui.getCurFocus(),1,#valid_focus)==valid_focus then
                     sidebar:show()
-                else
-                    sidebar:show(dfhack.gui.getCurViewscreen(true).parent)
                 end
             end
         end