1. Create the final size artwork for your drop down menu item. (I used 104 x 82 pixels)
2. Create a text box the same width but change the height to the minimum or off state. (I used 40 pixels)
3. Fill the text box with your artwork, setting your 'Fitting' to Scale to Fill' and your position to 'Bottom/Centre'
4. Change the text padding on your active state and rollover state to the a specific number that shows all of the original size of the artwork. (I used Space Before = 50)
5. Select the word 'text' that I used as a placeholder and change the colour to 'No Fill'
I hope this helps. (I tried to show all the pertinent widows in on screen shot)
