I love using the Slide a block method as shown here http://www.infografix.biz/?p=188
In FM12 I have been experiencing some unexpected behavor when sliding over a portal. The portal shows through the tab that slides over it. I have tried to work with moving the layers but have not found a consistent solution. What makes things worse is that it will work fine on the desktopa and show up different on the ipad. Andy body have experiance doing this in 12?