This bug still persists in v8.3.0. I re-posted this because Katalon team has done nothing for it. My previous post was automatically closed 365 days after the last reply. In this couple of days, I wrote fair amount of code in Katalon Studio. This bug irritated me very much.
See the following video where you can see how bad this bug is.
I checked Preferences > General > Appearance > Colors and Fonts to check which Font is used for Java Editor. I found Monaco 11 is the default choice of Katalon Studio 8.3.0.