Improvement of the calculation of the usable width of current window fixes #2545

autoload/vimtex/fold/envs.vim

@@ -82,8 +82,37 @@ function! s:folder.text(line, level) abort dict " {{{1
   endif
 
   let width = winwidth(0)
-        \ - (&number ? &numberwidth : 0)
-        \ - str2nr(matchstr(&foldcolumn, '\d\+$'))
+  let numberwidth = max([&numberwidth, strlen(line('$')) + 1])
+  let numwidth = (&number || &relativenumber) ? numberwidth : 0
+  let foldwidth = str2nr(matchstr(&foldcolumn, '\d\+$'))
+
+  if &signcolumn == 'yes'
+    let signwidth = 2
+  elseif &signcolumn =~ 'yes'
+    let signwidth = &signcolumn
+    let signwidth = split(signwidth, ':')[1]
+    let signwidth *= 2  " each signcolumn is 2-char wide
+  elseif &signcolumn == 'auto'
+    let supports_sign_groups = has('nvim-0.4.2') || has('patch-8.1.614')
+    let signlist = execute(printf('sign place ' . (supports_sign_groups ? 'group=* ' : '') . 'buffer=%d', bufnr('')))
+    let signlist = split(signlist, "\n")
+    let signwidth = len(signlist) > 2 ? 2 : 0
+  elseif &signcolumn =~ 'auto'
+    let signwidth = 0
+    if len(sign_getplaced(bufnr(),{'group':'*'})[0].signs)
+      let signwidth = 0
+      for l:sign in sign_getplaced(bufnr(),{'group':'*'})[0].signs
+        let lnum = l:sign.lnum
+        let signs = len(sign_getplaced(bufnr(),{'group':'*', 'lnum':lnum})[0].signs)
+        let signwidth = (signs > signwidth ? signs : signwidth)
+      endfor
+    endif
+    let signwidth *= 2   " each signcolumn is 2-char wide
+  else
+    let signwidth = 0
+  endif
+
+  let width = width - numwidth - foldwidth - signwidth
 
   " Always make room for the label
   let width_rhs = 0