Add option to select side of Toc window location

README.md

@@ -150,6 +150,16 @@ Try `:help concealcursor` and `:help conceallevel` for details.
 
         let g:vim_markdown_toc_autofit = 1
 
+### Choose TOC window location
+
+-   `g:vim_markdown_toc_location`
+
+    Choose location of the TOC window: left or right.
+    By default it's `left`
+
+        let g:vim_markdown_toc_location = 'right'
+
+
 ### Text emphasis restriction to single-lines
 
 -   `g:vim_markdown_emphasis_multiline`

ftplugin/markdown.vim

@@ -392,7 +392,11 @@ function! s:Toc(...)
     if l:window_type ==# 'horizontal'
         lopen
     elseif l:window_type ==# 'vertical'
-        vertical lopen
+        if exists('g:vim_markdown_toc_location') && g:vim_markdown_toc_location ==# 'right'
+            vertical botright lopen
+        else
+            vertical topleft lopen
+        endif
         " auto-fit toc window when possible to shrink it
         if (&columns/2) > l:header_max_len && l:vim_markdown_toc_autofit == 1
             " header_max_len + 1 space for first header + 3 spaces for line numbers