Description:
When I select multiple items in the list of animation effects in Impress, I should be able to edit the features of all of them: 

Effect Category
Effect (if they're all in the same category)
Start
Main effect parameter, e.g. color or direction (if all items are the same effect)
Duration
Delay

But the current behaviour (v5.4.5.1) is to only support editing one animation effect at a time. Annoying!

Steps to Reproduce:
1. Create two animation effects for some slide
2. Select both effects on the list

Actual Results:  
All effect details gray-out

Expected Results:
The effect details should be editable, as described above


Reproducible: Always


User Profile Reset: No



Additional Info:


User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:59.0) Gecko/20100101 Firefox/59.0