Very basic balloon support.

This is a huge hack, setting it manually and never resetting it. Just
displaying the value (no breakdown) etc.

I'm tempted to drop this functionality altogether as it is of limited
use when you have the locals and watch windows.

autoload/vimspector/internal/balloon.vim

@@ -0,0 +1,34 @@
+" vimspector - A multi-language debugging system for Vim
+" Copyright 2018 Ben Jackson
+"
+" Licensed under the Apache License, Version 2.0 (the "License");
+" you may not use this file except in compliance with the License.
+" You may obtain a copy of the License at
+"
+"   http://www.apache.org/licenses/LICENSE-2.0
+"
+" Unless required by applicable law or agreed to in writing, software
+" distributed under the License is distributed on an "AS IS" BASIS,
+" WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+" See the License for the specific language governing permissions and
+" limitations under the License.
+
+
+" Boilerplate {{{
+let s:save_cpo = &cpo
+set cpo&vim
+" }}}
+
+function vimspector#internal#balloon#BalloonExpr()
+  " winnr + 1 because for *no good reason* winnr is 0 based here unlike
+  " everywhere else
+  " int() because for *no good reason* winnr is a string.
+  py3 _vimspector_session.ShowBalloon( int( vim.eval( 'v:beval_winnr' ) ) + 1,
+        \ vim.eval( 'v:beval_text' ) )
+  return ''
+endfunction
+
+" Boilerplate {{{
+let &cpo=s:save_cpo
+unlet s:save_cpo
+" }}}