I am using Rstudio Version 1.2.1555 on OSX. I want to use a custom theme and so I used Tm Theme Editor. I used Monokai theme with only small changes. The issue is that in the result does not look like the Tm Theme Editor preview.
Here is what the Theme editor preview says the code should look like:
This is because the R tokenizer used with the Tm Theme Editor differs slightly from that included in RStudio. So, while the colors should match, how they're used in the theme may differ in some places.