Is your feature request related to a problem? Please describe:

I sometimes miss dispellable debuffs because they're not prominent enough on my screen.

Describe the solution you'd like to see implemented:

I would like to be able to configure a glowing frame around a raid frame when the unit has a debuff that can be dispelled by me.

Describe alternatives you've considered:

I have already configured dispellable debuffs into a separate corner of the raid frame and increased their icon size. Sometimes, in the heat of battle, I still miss them though.

This is already an option. Please see the far right tab on the indicator configuration page and enable the spell highlight animation option. Cheers.

I'm probably super-blind, but I can't seem to find it :/ Can you show me a screenshot, please?

Unfortunately I cannot right now, I'm away from my computer at a funeral for a few more days. You are looking for an option called "Indicator Glow Effect" on the "Animations" tab in the indicator configuration page. It's definitely there, I can promise you.