[Improvement] RStudio 1.3 changes (currently in Preview)

[luciorq]

Hello,

This is a great project and I would like to help improve it for the next release of RStudio.

I'm reporting a future ahead note that with RStudio 1.3, currently in release Preview, will need some changes, including work in the new Tutorial tab.

I will what I have detected so far:

1. "Start tutorial" buttons aren't colored Tutorial tab
2. "Scroll bars" aren't colored Tutorial Tab
   
3. The arrow used to see additional files, when you have enough open, has changed with the "Max,Min buttons" in the Source Panel
   
   • This also happens if you have several open documents in a new window
     

Thanks and best regards!

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Currently tested on RStudio Server Preview 1.3.887 for Ubuntu 18.04 on Google Chrome v80 browser
rscodeio v0.0.1