diff --git a/src/testdir/test_display.vim b/src/testdir/test_display.vim
index 5b08e84..1332ab5 100644
--- a/src/testdir/test_display.vim
+++ b/src/testdir/test_display.vim
@@ -471,9 +471,9 @@
   CheckScreendump
 
   let lines =<< trim END
-    set display=lastline
+    set display=lastline smoothscroll scrolloff=0
     call setline(1, [
-      \'aaaaa'->repeat(100),
+      \'aaaaa'->repeat(150),
       \'bbbbb '->repeat(7) .. 'ccccc '->repeat(7) .. 'ddddd '->repeat(7)
     \])
   END
@@ -481,11 +481,23 @@
   call writefile(lines, 'XdispLongline', 'D')
   let buf = RunVimInTerminal('-S XdispLongline', #{rows: 14, cols: 35})
 
-  call term_sendkeys(buf, "482|")
+  call term_sendkeys(buf, "736|")
   call VerifyScreenDump(buf, 'Test_display_long_line_1', {})
+
+  " The correct part of the last line is moved into view.
   call term_sendkeys(buf, "D")
   call VerifyScreenDump(buf, 'Test_display_long_line_2', {})
 
+  " "w_skipcol" does not change because the topline is still long enough
+  " to maintain the current skipcol.
+  call term_sendkeys(buf, "g04l11gkD")
+  call VerifyScreenDump(buf, 'Test_display_long_line_3', {})
+
+  " "w_skipcol" is reset to bring the entire topline into view because
+  " the line length is now smaller than the current skipcol + marker.
+  call term_sendkeys(buf, "x")
+  call VerifyScreenDump(buf, 'Test_display_long_line_4', {})
+
   call StopVimInTerminal(buf)
 endfunc