fix(api): redraw after setting minimal style

Problem: No explicit redraw after setting style=minimal in nvim_open_win or
nvim_win_set_config, which may cause it to appear like it's not set.

Solution: call changed_window_setting after applying the style, which should be
enough for these options.

src/nvim/api/win_config.c

@@ -24,6 +24,7 @@
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
 #include "nvim/memory_defs.h"
+#include "nvim/move.h"
 #include "nvim/option.h"
 #include "nvim/option_vars.h"
 #include "nvim/pos_defs.h"
@@ -345,6 +346,7 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(win_config) *config, Err
   if (fconfig.style == kWinStyleMinimal) {
     win_set_minimal_style(wp);
     didset_window_options(wp, true);
+    changed_window_setting(wp);
   }
   rv = wp->handle;
 
@@ -672,6 +674,7 @@ void nvim_win_set_config(Window window, Dict(win_config) *config, Error *err)
   if (HAS_KEY_X(config, style) && fconfig.style == kWinStyleMinimal) {
     win_set_minimal_style(win);
     didset_window_options(win, true);
+    changed_window_setting(win);
   }
   if (fconfig._cmdline_offset < INT_MAX) {
     cmdline_win = win;

test/functional/api/window_spec.lua

@@ -2316,6 +2316,41 @@ describe('API/win', function()
         )
       )
     end)
+
+    it('redraws after setting minimal style', function()
+      local screen = Screen.new(10, 10)
+      -- Autocommand processes pending redraws earlier than when minimal style is set, so it doesn't
+      -- implicitly rely on those.
+      exec([[
+        set cursorline cursorcolumn number
+        autocmd WinNew * ++once redraw | let g:triggered = 1
+      ]])
+      screen:expect([[
+        {15:  1 }{21:^        }|
+        {1:~           }|*8
+                    |
+      ]])
+      api.nvim_open_win(0, false, { style = 'minimal', split = 'below' })
+      eq(1, eval('g:triggered'))
+      screen:expect([[
+        {15:  1 }{21:^        }|
+        {1:~           }|*2
+        {2:[No Name]   }|
+                    |*4
+        {2:[No Name]   }|
+                    |
+      ]])
+      -- Also check nvim_win_set_config: only set style to avoid redraws from other config fields.
+      api.nvim_win_set_config(0, { style = 'minimal' })
+      screen:expect([[
+        ^            |
+                    |*2
+        {3:[No Name]   }|
+                    |*4
+        {2:[No Name]   }|
+                    |
+      ]])
+    end)
   end)
 
   describe('set_config', function()