I think could be the best add on with a few tweaks. It very simplistic which is a great thing . there's been some go I d suggestions and mine are things that would make more functional and not take away from the simplistic flow.
The 1 time I want to be a lefty ;) . I'm right and mostly on a tablet or phone so when I highlight I r double click the yellow popup is under my hand. It sounds minor but enough of an inconvenience that I will need to continue my search if a future update is not added for an option for choosing the popup side.
Doesn't need to be fixed as it's not broke but I don't like the delay and inconvenience. I wish Samsung would make a feature when you hover the Pen over a word the definition would pop up as they have pictures and hyperlinks. I think developer has done great job and would love to continue using but the amount I utilize now since getting larger phone I am only the option of some costly clunky app that's way overkill for just what's done here solely with a tiny addon.
If wanting to elaborate on addon as maybe a Pro version, I would say the Ability for us to choose or enter the site used to lookup, Choice from a few colors or a pallete of popup box, Addition of a speaker icon by word to hear it sounded out.
Now the last may be too much to ask for but that's basically what I or know others utilize. Not all these games,words of the day,share the word with everyone and just so much distracting and phone memory using features.
While browsing all needed is - reading,what's that word, click, what's the meaning, how's it sound, continue reading. Perfect App!