Highlight of the droppable zone

Hello everyone. I have interesting problem I want to Highlight the droppable 
zone, the simplest solution is: give the droppable area a hover class. But 
there is a problem, in this case the droppable arrea is the png image and I 
don't want to cover image by hover class. The best way will be transparent or 
half transparent hover class, but i don't know is it possible? 
Is it possible?
I start thinkig about the problem, and maybe using effect Highlight will give a 
solution? I start looking on the code effect Highlight and i saw that this not 
gone to work because Highlight effect temporary change background image to 
none, then sets Highlight and after that restore backgroundimage. So is it 
possible to give a droppable a hover class that not cover the "context" of the 
droppable? 
Best Wishes 
Grzegorz Ślusarek

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