make preview winodow focusable (closes #202)

lua/fzf-lua/previewer/builtin.lua

@@ -194,7 +194,7 @@ function Previewer.base:scroll(direction)
   if preview_winid < 0 or not direction then return end
 
   if direction == 0 then
-    utils.nvim_win_call(preview_winid, function()
+    vim.api.nvim_win_call(preview_winid, function()
       -- for some reason 'nvim_win_set_cursor'
       -- only moves forward, so set to (1,0) first
       api.nvim_win_set_cursor(0, {1, 0})
@@ -221,7 +221,7 @@ function Previewer.base:scroll(direction)
       -- local input = direction > 0 and [[]] or [[]]
       -- ^D = 0x04, ^U = 0x15 ('g8' on char to display)
       local input = ('%c'):format(utils._if(direction>0, 0x04, 0x15))
-      utils.nvim_win_call(preview_winid, function()
+      vim.api.nvim_win_call(preview_winid, function()
         vim.cmd([[norm! ]] .. input)
         utils.zz()
       end)

lua/fzf-lua/win.lua

@@ -390,9 +390,10 @@ function FzfWin:preview_layout()
     -- only use relative when using splits
     local winopts = {relative = 'editor', focusable = false, style = 'minimal'}
     if self.winopts.split then
-      winopts = {relative = 'win', win = self.fzf_winid, focusable = false, style = 'minimal'}
+      winopts.relative = 'win'
     end
     local preview_opts = vim.tbl_extend('force', winopts, {
+        focusable = true,
         anchor = anchor,
         width = width,
         height = height,