Question

If I hover the mouse on any word of a Ruby file, I get a tooltip message.

A screenshot of that popup message is at popup message.

cat ~/.gvimrc returns:

function! SyntaxBalloon()
    let synID   = synID(v:beval_lnum, v:beval_col, 0)
    let groupID = synIDtrans(synID)
    let name    = synIDattr(synID, "name")
    let group   = synIDattr(groupID, "name")
    return name . "\n" . group
endfunction

set balloonexpr=SyntaxBalloon()
set ballooneval

"how syntax highlighting groups for word under cursor
nmap <F2> :call <SID>SynStack()<CR>
function! <SID>SynStack()
    if !exists("*synstack")
        return
    endif
    echo map(synstack(line('.'), col('.')), 'synIDattr(v:val, "name")')
endfunc

Answer 1

You’re are using vim-ruby I guess. Well, this plugin defined a balloonexpr. You can read it here. Personally I find it quite annoying so I have disabled it with:

setlocal balloonexpr=

in my .vim/after/ftplugin/ruby.vim file.