	Platforms	Pros	Cons
Atom	Cross	built-in markdown file preview
Emacs	Cross
Gedit	Cross	print preview	no code folding
Geany	Cross	print preview; Terminal
IntelliJ IDEA	Cross
Notepad++	Win	print line numbers, Right-click menu	R syntax highlight not work with most themes
Qt Creator	Cross	split a window (even same file)
RStudio	Cross	folding, best IDE for R coding	not support drag and drop a file but SendTo works
Sublime	Cross
vi	Cross
Visual Studio Code	Cross	Integrated Terminal, Markdown preview	Should not include minimap function

HTML editors: see here.

Visual Studio Code

Theme