add feature to customize highlight for floating hover window (#966)

* add g:LanguageClient_floatingHoverHighlight

* make g:LanguageClient_floatingHoverHighlight accept arbitrary highlights

Author: 110y

autoload/LanguageClient.vim

@@ -259,7 +259,7 @@ function! s:AddHighlights(source, highlights) abort
 endfunction
 
 " Get an variable value.
-" Get variable from uffer local, or else global, or else default, or else v:null.
+" Get variable from buffer local, or else global, or else default, or else v:null.
 function! s:GetVar(...) abort
     let name = a:1
 
@@ -404,7 +404,8 @@ function! s:OpenHoverPreview(bufname, lines, filetype) abort
 
         execute 'noswapfile edit!' a:bufname
 
-        setlocal winhl=Normal:CursorLine
+        let float_win_highlight = s:GetVar('LanguageClient_floatingHoverHighlight', 'Normal:CursorLine')
+        execute printf('setlocal winhl=%s', float_win_highlight)
     elseif display_approach ==# 'popup_win'
         let pop_win_id = popup_atcursor(a:lines, {})
         call setbufvar(winbufnr(pop_win_id), '&filetype', a:filetype)

doc/LanguageClient.txt

@@ -358,7 +358,13 @@ supported. Check by running >
 Default: 1 when a floating window is supported, otherwise 0
 Valid Options: 1 | 0
 
-2.26 g:LanguageClient_usePopupHover           *g:LanguageClient_usePopupHover*
+2.27 g:LanguageClient_floatingHoverHighlight *g:LanguageClient_floatingHoverHighlight*
+
+Control how floating window hover highlights are displayed.
+
+Default: Normal:CursorLine
+
+2.28 g:LanguageClient_usePopupHover           *g:LanguageClient_usePopupHover*
 
 When the value is set to 1, |LanguageClient#textDocument_hover()| opens
 documentation in a popup window instead of preview.
@@ -369,7 +375,7 @@ supported, which is supported only in vim 8.2+. Check by running >
 Default: 1 when a popup window is supported, otherwise 0
 Valid Options: 1 | 0
 
-2.27 g:LanguageClient_virtualTextPrefix     *g:LanguageClient_virtualTextPrefix*
+2.29 g:LanguageClient_virtualTextPrefix     *g:LanguageClient_virtualTextPrefix*
 
 When the value is set to a valid string and |g:LanguageClient_useVirtualText| is
 enabled, all virtual text lines are prefixed with the defined string.
@@ -379,14 +385,14 @@ supported.
 Default: Empty string ('')
 Valid Options: string
 
-2.28 g:LanguageClient_diagnosticsMaxSeverity  *g:LanguageClient_diagnosticsMaxSeverity*
+2.30 g:LanguageClient_diagnosticsMaxSeverity  *g:LanguageClient_diagnosticsMaxSeverity*
 
 Maximum severity to show diagnostic messages.
 
 Default: "Hint"
 Valid options: "Error" | "Warning" | "Information" | "Hint"
 
-2.29 g:LanguageClient_echoProjectRoot  *g:LanguageClient_echoProjectRoot*
+2.31 g:LanguageClient_echoProjectRoot  *g:LanguageClient_echoProjectRoot*
 
 Whether to echo messages in vim of the form: "Project root: /home/user/myproject" when
 the root of a project is detected using g:LanguageClient_rootMarkers.