Fixes #5043 - `View.ScrollBars` now only show if they fit - Fixes `View.Viewport` bug by tig · Pull Request #5045 · gui-cs/Terminal.Gui

tig · 2026-04-21T19:29:10Z

Fixes

Pull request overview

This PR targets issue #5043 by preventing built-in scrollbars from becoming visible when there isn’t enough space to render them without consuming the entire content area, and by addressing a Viewport/adornment interaction that could incorrectly grow Frame when re-applying the current Viewport.

Changes:

Add scrollbar visibility guards (and a minimum-size rule) so scrollbars only show when they can fit.
Adjust View.SetViewport behavior and add viewport/adornment regression tests for the “adornments consume viewport” scenario.
Update Shortcut/Menu example and unit test code to accommodate the behavior changes.

… develop

Refactor Shortcut and related code to make CommandView nullable (View?) and update all usages to handle null values safely. Update property setters, event handlers, layout logic, and tests to use null-safe access. Initialize HelpView and KeyView with default Frames. Clean up redundant null checks and improve robustness against null reference exceptions when CommandView is replaced or disposed.

- Remove BorderStyle from TreeViewFileSystem tree view - Prevent invalid viewport/frame updates in View - Refine scrollbar visibility checks for valid content area - Remove quit key binding from MenuBar, comment out in PopoverMenu - Hide scrollbars if visible content size < 2 in auto mode

Refactored TreeViewFileSystem to use Runnable and improved layout logic. Enhanced View.Content.cs to prevent Frame growth when adornments consume the viewport. Expanded ViewportTests with cases for adornment edge cases. Applied code style and correctness improvements.

Copilot

Pull request overview

This PR targets issue #5043 by preventing built-in scrollbars from becoming visible when there isn’t enough space to render them without consuming the entire content area, and by addressing a Viewport/adornment interaction that could incorrectly grow Frame when re-applying the current Viewport.

Changes:

Add scrollbar visibility guards (and a minimum-size rule) so scrollbars only show when they can fit.
Adjust View.SetViewport behavior and add viewport/adornment regression tests for the “adornments consume viewport” scenario.
Update Shortcut/Menu example and unit test code to accommodate the behavior changes.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
Tests/UnitTestsParallelizable/Views/ShortcutTests.cs	Updates Shortcut tests for `CommandView` nullability/layout expectations.
Tests/UnitTestsParallelizable/Views/ShortcutTests.KeyDown.cs	Updates Shortcut input tests; adds null-conditional usage in assertions.
Tests/UnitTestsParallelizable/Views/EnableForDesignEventTests.cs	Uses null-forgiving operator when casting `CommandView`.
Tests/UnitTestsParallelizable/ViewBase/Layout/ViewportTests.cs	Adds regression tests ensuring `Viewport = Viewport` doesn’t grow `Frame` when adornments consume viewport.
Terminal.Gui/Views/Shortcut.cs	Makes `CommandView` nullable and adds default Frames to subviews; adjusts layout logic.
Terminal.Gui/Views/ScrollBar/ScrollBar.cs	Prevents Auto scrollbars from showing when too small to render both buttons.
Terminal.Gui/Views/Menu/MenuBar.cs	Tweaks design-time Quit menu item creation.
Terminal.Gui/ViewBase/View.ScrollBars.cs	Adds `VisibleChanging` cancellation logic to prevent scrollbars showing when they can’t fit.
Terminal.Gui/ViewBase/View.Content.cs	Adds an early-return guard in `SetViewport` for “invalid” sizes / no-op scenarios.
Terminal.Gui/ViewBase/Adornment/AdornmentImpl.cs	Adds (commented-out) debug assertion concept for unreasonable thickness values.
Examples/UICatalog/Scenarios/TreeViewFileSystem.cs	Updates layout and replaces `Window` with `Runnable` for the scenario root.
Examples/UICatalog/Scenarios/Shortcuts.cs	Updates event handler/lambda parameters and adds null-conditional access for `CommandView`.
Examples/UICatalog/Scenarios/PopoverMenus.cs	Makes checkbox cast/assignment safe via `as` + null-conditional.

Comments suppressed due to low confidence (2)

Terminal.Gui/Views/Shortcut.cs:260

CommandView is now nullable, but this block dereferences it (CommandView.SuperView, Add(CommandView)) based on CommandView?.Visible == true. This will produce nullable warnings and can still pass a null to Add(...). Consider caching View commandView = CommandView! after a null check, or keep CommandView non-nullable if it is required by design.

        if (CommandView?.Visible == true)
        {
            if (CommandView.SuperView is null)
            {
                Add (CommandView);
                SetCommandViewDefaultLayout ();

Examples/UICatalog/Scenarios/Shortcuts.cs:339

The condition uses framedShortcut.CommandView?.Margin is { }, but inside the block framedShortcut.CommandView is dereferenced without a null check. With CommandView now nullable this will produce nullable warnings. Consider caching View commandView = framedShortcut.CommandView!; after an explicit not-null check, then use commandView inside the block.

        if (framedShortcut.CommandView?.Margin is { })
        {
            framedShortcut.CommandView.SchemeName = SchemeManager.SchemesToSchemeName (Schemes.Dialog);
            framedShortcut.HelpView.SchemeName = SchemeManager.SchemesToSchemeName (Schemes.Error);
            framedShortcut.KeyView.SchemeName = SchemeManager.SchemesToSchemeName (Schemes.Base);

When the scheme name is "Accent", the code now derives the accent scheme from the "Base" scheme using the driver's default attribute, rather than returning the named "Accent" scheme directly. This ensures consistent accent theming based on the current base scheme.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…inal.Gui into issue-5043-scrollbar

Removed null check and updated usages to support CommandView being null. Used null-conditional operators to prevent exceptions and set Title to an empty string when CommandView is null.

… layout logic Removed arbitrary screenX4 upper bounds in dimension and layout calculations, using int.MaxValue instead. This change affects maximum content dimension, text formatting constraints, and layout for centered and anchored subviews, improving flexibility and correctness for large dimension scenarios.

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

Terminal.Gui/Views/Shortcut.cs:446

The XML docs for CommandView still include an ArgumentNullException <exception> tag, but the setter no longer throws on null and the property is now nullable. Please update the docs to reflect the actual behavior (or reintroduce the null guard if CommandView is intended to be non-null).

    /// <summary>
    ///     Gets or sets the View that displays the command text and hotkey.
    /// </summary>
    /// <exception cref="ArgumentNullException"></exception>
    /// <remarks>

- Arrangement scenario now sets SchemeName via SchemeManager instead of assigning a custom Scheme directly. - DropDownList overrides OnMouseEvent to handle popover activation when ReadOnly and left mouse button is pressed.

Fix Accent scheme fallback, cleanup, and disposal logic - Derive Accent scheme from Base if missing background color - Simplify ConstrainToSize assignment in DimAuto.cs - Reformat namespace in View.Content.cs - Use _commandView field consistently in Shortcut disposal

Copilot

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

Terminal.Gui/Views/Shortcut.cs:519

CommandView was changed from non-nullable to View? and the setter no longer rejects null, but the class docs/remarks describe Shortcut as a composite containing a CommandView and command dispatch relies on it as the relay target. This is a public API surface change for nullable-reference-type consumers and may be unintentionally loosening an invariant. If null is not a supported state, consider restoring the non-nullable type + ThrowIfNull; if it is supported, consider updating the XML docs and ensuring all callers (and derived types like MenuItem) have a clear contract for the null case.

    public View? CommandView
    {
        get => _commandView;
        set
        {
            // Clean up old
            _commandView?.GettingAttributeForRole -= SubViewOnGettingAttributeForRole;
            Remove (_commandView);
            _commandView?.Dispose ();

            // Set new
            _commandView = value;

#if DEBUG
            if (string.IsNullOrEmpty (_commandView?.Id))
            {
                _commandView?.Id = "_commandView";
            }
#endif
            _commandView?.GettingAttributeForRole += SubViewOnGettingAttributeForRole;

            // If the CommandView has a hotkey, we use that. Otherwise, we use '_' to indicate the hotkey is in the Title.
            if (_commandView?.HotKey != Key.Empty)
            {
                HotKeySpecifier = (Rune)'\xffff';
            }
            else
            {
                HotKeySpecifier = (Rune)'_';
            }
            Title = _commandView?.Text ?? string.Empty;

            UpdateKeyBindings (Key.Empty);
            UpdateMouseBindings ();
            ShowHide ();
        }

…ort no-op case Agent-Logs-Url: https://github.com/gui-cs/Terminal.Gui/sessions/7f22400b-e587-4b21-a4a7-90a776f8784d Co-authored-by: tig <585482+tig@users.noreply.github.com>

BDisp

That sounds good to me. I just have two questions that I'm a little unsure about.

tig added 4 commits April 21, 2026 09:23

Merge branch 'develop' of https://github.com/gui-cs/Terminal.Gui into…

f333cab

… develop

tig requested a review from Copilot April 21, 2026 19:29

Copilot started reviewing on behalf of tig April 21, 2026 19:29 View session

Copilot AI reviewed Apr 21, 2026

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tig and others added 4 commits April 21, 2026 13:57

Update Terminal.Gui/ViewBase/Adornment/AdornmentImpl.cs

f23d2a4

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Merge branch 'issue-5043-scrollbar' of https://github.com/gui-cs/Term…

15df289

…inal.Gui into issue-5043-scrollbar

Allow CommandView to be nullable in Shortcut

752f403

Removed null check and updated usages to support CommandView being null. Used null-conditional operators to prevent exceptions and set Title to an empty string when CommandView is null.

tig requested a review from BDisp April 21, 2026 20:02

tig requested a review from Copilot April 21, 2026 20:12

Copilot started reviewing on behalf of tig April 21, 2026 20:12 View session

Copilot AI reviewed Apr 21, 2026

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Comment thread Terminal.Gui/ViewBase/Layout/DimAuto.cs Outdated

Comment thread Terminal.Gui/ViewBase/View.Drawing.Scheme.cs Outdated

Comment thread Terminal.Gui/ViewBase/View.Content.cs Outdated

Comment thread Terminal.Gui/Views/Shortcut.cs Outdated

tig added 2 commits April 21, 2026 15:01

Refactor color scheme and DropDownList mouse handling

c3bbd7e

- Arrangement scenario now sets SchemeName via SchemeManager instead of assigning a custom Scheme directly. - DropDownList overrides OnMouseEvent to handle popover activation when ReadOnly and left mouse button is pressed.

Code review fixes.

4eed1d4

Fix Accent scheme fallback, cleanup, and disposal logic - Derive Accent scheme from Base if missing background color - Simplify ConstrainToSize assignment in DimAuto.cs - Reformat namespace in View.Content.cs - Use _commandView field consistently in Shortcut disposal

tig requested a review from Copilot April 21, 2026 21:16

Copilot started reviewing on behalf of tig April 21, 2026 21:16 View session

Copilot AI reviewed Apr 21, 2026

View reviewed changes

Comment thread Terminal.Gui/ViewBase/View.Content.cs

Copilot started work on behalf of tig April 21, 2026 21:34 View session

Copilot finished work on behalf of tig April 21, 2026 21:43

BDisp approved these changes Apr 21, 2026

View reviewed changes

Comment thread Terminal.Gui/ViewBase/View.ScrollBars.cs

Comment thread Terminal.Gui/ViewBase/View.ScrollBars.cs

tig merged commit 975c390 into develop Apr 22, 2026
11 checks passed

tig deleted the issue-5043-scrollbar branch April 22, 2026 14:39

This was referenced Apr 30, 2026

Bump Terminal.Gui from 2.0.0-develop.5264 to 2.0.1 Yuta-K19418/DataMorph#196

Merged

Bump Terminal.Gui from 2.0.0-develop.5038 to 2.0.1 PureKrome/SimpleAWS.S3.Downloader#62

Open

Bump the dotnet-dependencies group with 13 updates jntm7/pitterm#6

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This was referenced May 4, 2026

Bump Terminal.Gui from 2.0.0-develop.5039 to 2.0.1 MaciekWin3/TermKeyVault#129

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chore: Bump Terminal.Gui from 2.0.0-rc.5 to 2.0.1 bartul/imperium#125

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Bump Terminal.Gui from 1.19.0 to 2.0.1 jas88/RDMP#205

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tig commented Apr 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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tig commented Apr 21, 2026 •

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