patch 9.2.0190: Status line height mismatch in vertical splits

Problem:  When 'laststatus' changes, the status line can become
          misaligned.
Solution: Update last_status_rec() to calculate the maximum status line
          height required across all windows in a vertical row.

closes: #19688

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/dumps/Test_laststatus_vsplit_row_height2_1.dump

@@ -0,0 +1,8 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|[+3#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+| +0&&@36||+1&&| +0&&@36
+|[+1&&|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1| |~+0#4040ff13&| @35
+| +1#0000000&@37|[|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1
+| +0&&@74

src/testdir/dumps/Test_laststatus_vsplit_row_height3_1.dump

@@ -0,0 +1,8 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|[+3#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+| +0&&@36||+1&&| +0&&@36
+|~+0#4040ff13&| @35||+1#0000000&|[|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1
+|[|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1| @37
+| +0&&@74

src/testdir/dumps/Test_laststatus_vsplit_row_height_1.dump

@@ -0,0 +1,8 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|[+3#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+| +0&&@36||+1&&| +0&&@36
+|[+1&&|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1| |[|N|o| |N|a|m|e|]| @9|0|,|0|-|1| @9|A|l@1
+| +0&&@74

src/testdir/test_window_cmd.vim

@@ -2377,8 +2377,9 @@ endfunc
 " When shrinking a window and the only other window has 'winfixheight'
 " with 'winminheight'=0, freed rows must go to the wfh window.
 func Test_winfixheight_resize_wmh_zero()
-  set winminheight=0 laststatus=0
+  CheckFeature quickfix
 
+  set winminheight=0 laststatus=0
   let id1 = win_getid()
   copen
   let id2 = win_getid()
@@ -2438,4 +2439,61 @@ func Test_winfixheight_resize_wmh_zero()
   set winminheight& laststatus&
 endfunc
 
+" Test that setting 'laststatus' from 0 to 2 gives all windows in a vertical
+" split (FR_ROW) the same height and correct status line position.
+func Test_laststatus_vsplit_row_height()
+  CheckScreendump
+
+  let lines =<< trim END
+    set ls=0
+    vsplit
+    topleft new
+    wincmd _
+    set ls=2
+  END
+  call writefile(lines, 'XTestLaststatusVsplitRowHeight', 'D')
+  let buf = RunVimInTerminal('-S XTestLaststatusVsplitRowHeight', #{rows: 8})
+  call VerifyScreenDump(buf, 'Test_laststatus_vsplit_row_height_1', {})
+  call StopVimInTerminal(buf)
+endfunc
+
+" Test that when FR_ROW windows have different status line heights (due to
+" window-local 'statuslineopt'), content heights compensate so that total
+" rows are equal across the row.
+func Test_laststatus_vsplit_row_height_mixed_stlo()
+  CheckScreendump
+
+  let lines =<< trim END
+    set ls=0
+    setlocal stlo=fixedheight,maxheight:2
+    rightbelow vnew
+    topleft new
+    wincmd _
+    set ls=2
+  END
+  call writefile(lines, 'XTestLaststatusVsplitRowHeight2', 'D')
+  let buf = RunVimInTerminal('-S XTestLaststatusVsplitRowHeight2', #{rows: 8})
+  call VerifyScreenDump(buf, 'Test_laststatus_vsplit_row_height2_1', {})
+  call StopVimInTerminal(buf)
+endfunc
+
+" Same as above but with the stlo window on the right (second leaf in FR_ROW).
+func Test_laststatus_vsplit_row_height_mixed_stlo_reversed()
+  CheckScreendump
+
+  let lines =<< trim END
+    set ls=0
+    leftabove vnew
+    wincmd p
+    setlocal stlo=fixedheight,maxheight:2
+    topleft new
+    wincmd _
+    set ls=2
+  END
+  call writefile(lines, 'XTestLaststatusVsplitRowHeight3', 'D')
+  let buf = RunVimInTerminal('-S XTestLaststatusVsplitRowHeight3', #{rows: 8})
+  call VerifyScreenDump(buf, 'Test_laststatus_vsplit_row_height3_1', {})
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    190,
 /**/
     189,
 /**/

src/window.c

@@ -7654,8 +7654,78 @@ last_status_rec(frame_T *fr, int statusline)
     else if (fr->fr_layout == FR_ROW)
     {
 	// vertically split windows, set status line for each one
-	FOR_ALL_FRAMES(fp, fr->fr_child)
-	    last_status_rec(fp, statusline);
+	if (!statusline)
+	{
+	    FOR_ALL_FRAMES(fp, fr->fr_child)
+		last_status_rec(fp, statusline);
+	}
+	else
+	{
+	    frame_T	*fp2;
+	    int		max_stlh = 0;
+	    int		new_row_height;
+
+	    // Find the max status height needed across all leaf windows.
+	    FOR_ALL_FRAMES(fp, fr->fr_child)
+		if (fp->fr_win != NULL && fp->fr_win->w_status_height == 0)
+		{
+		    int h = statusline_height(fp->fr_win);
+		    if (h > max_stlh)
+			max_stlh = h;
+		}
+	    if (max_stlh == 0)
+		return;
+
+	    // Find a frame to take max_stlh lines from.
+	    fp2 = fr;
+	    while (fp2->fr_height - frame_minheight(fp2, NULL) < max_stlh)
+	    {
+		if (fp2 == topframe)
+		{
+		    emsg(_(e_not_enough_room));
+		    return;
+		}
+		if (fp2->fr_parent->fr_layout == FR_COL
+						&& fp2->fr_prev != NULL)
+		    fp2 = fp2->fr_prev;
+		else
+		    fp2 = fp2->fr_parent;
+	    }
+
+	    if (fp2 != fr)
+	    {
+		frame_new_height(fp2, fp2->fr_height - max_stlh,
+							FALSE, FALSE, FALSE);
+		new_row_height = fr->fr_height + max_stlh;
+	    }
+	    else
+		new_row_height = fr->fr_height;
+
+	    // Set status and content heights for all leaves.
+	    FOR_ALL_FRAMES(fp, fr->fr_child)
+	    {
+		if (fp->fr_win != NULL)
+		{
+		    wp = fp->fr_win;
+		    if (wp->w_status_height == 0)
+		    {
+			wp->w_status_height = statusline_height(wp);
+			win_new_height(wp,
+				  new_row_height - wp->w_status_height);
+			frame_fix_height(wp);
+			comp_col();
+			redraw_all_later(UPD_SOME_VALID);
+			if (abs(wp->w_height - wp->w_prev_height) == 1)
+			    wp->w_prev_height = wp->w_height;
+		    }
+		}
+		else
+		    last_status_rec(fp, statusline); // nested frames
+	    }
+
+	    fr->fr_height = new_row_height;
+	    win_comp_pos();
+	}
     }
     else
     {