Fixes #5237. Fix Markdown table row height calculation

Terminal.Gui/Views/Markdown/MarkdownView.Layout.cs

@@ -88,6 +88,10 @@ private void BuildRenderedLines ()
                 };
                 tableView.Recalculate (tableLayoutWidth);
 
+                // Capture the rendered height BEFORE Add() — Add triggers EndInit → Layout
+                // which may recalculate the table at a stale content width, corrupting RenderedHeight.
+                int tableHeight = tableView.RenderedHeight;
+
                 // Forward link clicks from the table to this Markdown view's LinkClicked event.
                 tableView.LinkClicked += (_, e) =>
                                          {
@@ -108,9 +112,6 @@ private void BuildRenderedLines ()
                 _tableViews.Add (tableView);
                 Add (tableView);
 
-                // Use actual table height (accounts for word-wrapped rows at current width)
-                int tableHeight = tableView.RenderedHeight;
-
                 // Reserve placeholder lines so content height is correct
                 for (var i = 0; i < tableHeight; i++)
                 {

Tests/UnitTestsParallelizable/Views/Markdown/TableHeightInvestigation.cs

@@ -0,0 +1,116 @@
+using Terminal.Gui;
+using Terminal.Gui.App;
+using Terminal.Gui.Drawing;
+using Terminal.Gui.ViewBase;
+using Terminal.Gui.Views;
+using Xunit;
+
+namespace ViewsTests.Markdown;
+
+public class TableHeightInvestigation
+{
+    // Copilot
+
+    [Theory]
+    [InlineData (80)]
+    [InlineData (100)]
+    [InlineData (120)]
+    [InlineData (150)]
+    public void Table_RenderedHeight_Matches_Frame_Height_After_Layout (int screenWidth)
+    {
+        // Copilot
+        // Regression test: RenderedHeight must match Frame.Height after layout.
+        // Previously, Add(tableView) triggered EndInit → Layout → Recalculate at stale width,
+        // corrupting RenderedHeight and causing extra blank lines after the table.
+        string markdown = @"## Available Clets
+
+| Alias | Description | Options |
+|-------|-------------|---------|
+| select | Presents a list of options and returns the text of the selected item. | --options, args ... |
+| text | Prompts for free-form text input and returns the entered string. | |
+| multiline-text, mt | Prompts for multi-line text input and returns the entered string. | |
+| int | Prompts for an integer value using a numeric spinner. | --step |
+| decimal | Prompts for a decimal value using a numeric spinner. | --step |
+| confirm | Prompts for a yes/no confirmation and returns a boolean | --prompt |
+| date | Prompts for a date and returns an ISO-8601 date string (YYYY-MM-DD). | |
+| time | Prompts for a time and returns an ISO-8601 time string (HH:MM:SS). | |
+| duration | Prompts for a duration and returns an ISO-8601 duration string (e.g. PT1H30M). | |
+| color | Prompts for a color and returns a hex string (@rrggbb). | |
+| multi-select | Presents a list of options with checkboxes and returns the selected texts. | --options, args ... |
+| attribute-picker, attribute | Prompts for text attributes (Foreground, Background, style) and returns a JSON object. | |
+| pick-file, file | Opens a file picker dialog and returns the selected file path(s). | --multi, --root, --filter |
+| pick-directory, dir | Opens a directory picker dialog and returns the selected directory path. | --root |
+| linear-range, range | Presents a LinearRange (single, multi, or bounded range) over a list of labelled options and returns the selection. | --mode, --options, --orientation, --range-kind, --allow-empty, --hide-legends, args ... |
+| md, markdown | Browse and render Markdown files with link navigation and syntax highlighting. | --theme, --cat, --no-browse, args |
+| help | Shows help for clet commands. | args ... |
+
+Click for details: select, text";
+
+        IApplication app = Application.Create ();
+        app.Init (DriverRegistry.Names.ANSI);
+        app.Driver!.SetScreenSize (screenWidth, 50);
+
+        Runnable window = new () { Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.None };
+
+        Terminal.Gui.Views.Markdown mv = new () { Text = markdown, Width = Dim.Fill (), Height = Dim.Fill () };
+        window.Add (mv);
+
+        app.Begin (window);
+        app.LayoutAndDraw ();
+
+        List<MarkdownTable> tableViews = mv.SubViews.OfType<MarkdownTable> ().ToList ();
+        Assert.Single (tableViews);
+
+        MarkdownTable table = tableViews [0];
+
+        // The table's RenderedHeight must equal its Frame.Height after layout
+        Assert.Equal (table.RenderedHeight, table.Frame.Height);
+
+        window.Dispose ();
+        app.Dispose ();
+    }
+
+    [Fact]
+    public void Table_LineCount_Consistent_After_Resize ()
+    {
+        // Copilot
+        // Regression test: resizing should not produce extra blank lines after a table.
+        string markdown = @"## Test
+
+| Alias | Description | Options |
+|-------|-------------|---------|
+| select | Presents a list of options and returns the text of the selected item. | --options, args ... |
+| multiline-text, mt | Prompts for multi-line text input and returns the entered string. | |
+| linear-range, range | Presents a LinearRange (single, multi, or bounded range) over a list of labelled options and returns the selection. | --mode, --options, --orientation, --range-kind, --allow-empty, --hide-legends, args ... |
+
+End";
+
+        IApplication app = Application.Create ();
+        app.Init (DriverRegistry.Names.ANSI);
+        app.Driver!.SetScreenSize (100, 30);
+
+        Runnable window = new () { Width = Dim.Fill (), Height = Dim.Fill (), BorderStyle = LineStyle.None };
+
+        Terminal.Gui.Views.Markdown mv = new () { Text = markdown, Width = Dim.Fill (), Height = Dim.Fill () };
+        window.Add (mv);
+
+        app.Begin (window);
+        app.LayoutAndDraw ();
+
+        int initialLineCount = mv.LineCount;
+
+        // Resize by 1 column - should not dramatically change line count
+        app.Driver.SetScreenSize (101, 30);
+        window.SetNeedsLayout ();
+        app.LayoutAndDraw ();
+
+        int resizedLineCount = mv.LineCount;
+
+        // The line counts should be equal or differ by at most 1 (due to wrapping boundary)
+        // Previously the initial count could be many lines too large.
+        Assert.InRange (Math.Abs (initialLineCount - resizedLineCount), 0, 1);
+
+        window.Dispose ();
+        app.Dispose ();
+    }
+}