vim-patch:9.1.1839: Window may have wrong height if resized from another tabpage (#36093)

Problem:  Window may have wrong height if resized from another tabpage.
Solution: Improve check for whether a tabline has been added (zeertzjq).

fixes: vim/vim#18518
closes: vim/vim#18519

bd3b958027
(cherry picked from commit 28355050a8)

test/old/testdir/test_window_cmd.vim

@@ -2263,6 +2263,7 @@ endfunc
 
 func Test_winfixsize_vsep_statusline()
   CheckScreendump
+
   let lines =<< trim END
     set noequalalways splitbelow splitright
     vsplit
@@ -2307,4 +2308,22 @@ func Test_winfixsize_vsep_statusline()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_resize_from_another_tabpage()
+  CheckScreendump
+
+  let lines =<< trim END
+    set laststatus=2
+    vnew
+    let w = win_getid()
+    tabnew
+    call win_execute(w, 'vertical resize 20')
+    tabprev
+  END
+  call writefile(lines, 'XTestResizeFromAnotherTabpage', 'D')
+  let buf = RunVimInTerminal('-S XTestResizeFromAnotherTabpage', #{rows: 8})
+  call VerifyScreenDump(buf, 'Test_resize_from_another_tabpage_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab