Abandoned - Fixes #3691. Adds Popover

[tig]

Fixes

• Fixes Popover - A consistent way of enabling a Subview to popup outside of a View #3691

• Fixes ShadowView throws System.IndexOutOfRangeException if left is less than zero. #3757

Proposed Changes/Todos

• Prototype in View Experiments the concept described in Popover - A consistent way of enabling a Subview to popup outside of a View #3691 to prove concept.
• Prototype in Bars to show how ContextMenu and MenuBar could utilize
• Re-implement ContextMenu using MenuV2 - Initially no cascading menus for simplicity
• Re-implement AutocompletePopup
• Re-implement Combobox
• Add more ShadowView unit tests (see ShadowView throws System.IndexOutOfRangeException if left is less than zero. #3757)

Future PRs

• Replace Menu and MenuBar using Bar (aka finish Menuv2

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui - if you use Visual Studio, hit CTRL-K-D to automatically reformat your files before committing.
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working

[tig]

FWIW, here's the API in action (the prototype for the File menubar item in Bars):

var fileMenuBarItem = new Shortcut
{
    Title = "_File",
    HelpText = "File Menu",
    Key = Key.D0.WithAlt,
};

fileMenuBarItem.Accept += (sender, args) =>
                          {
                              var fileMenu = new Menuv2
                              {
                                  Id = "fileMenu",
                              };
                              ConfigureMenu (fileMenu);
                              fileMenu.VisibleChanged += (sender, args) =>
                                                         {
                                                             if (Application.Popover == _popoverMenu && Application.Popover is { Visible: false })
                                                             {
                                                                 Application.Popover?.Dispose ();
                                                                 Application.Popover = null;
                                                             }
                                                         };
                              Application.Popover = fileMenu;
                              Rectangle screen = fileMenuBarItem.FrameToScreen ();
                              fileMenu.X = screen.X;
                              fileMenu.Y = screen.Y + screen.Height;
                              fileMenu.Visible = true;

                          };

Here's the entirety of the new API (on Application):

    /// <summary>Gets or sets the Application Popover View.</summary>
    /// <remarks>
    ///     <para>
    ///         To show or hide the Popover, set it's <see cref="View.Visible"/> property.
    ///     </para>
    /// </remarks>
    public static View? Popover

[tig]

[tig]

Kinda cool. Mouse wheel will now be able to nav within a Bar (or Menu).

[tig]

A new ContextMenuv2 implementation.

TextField now uses it instead of the old one.

[tig]

Here's how this PR current works:

There's a new property on Application:

    /// <summary>Gets or sets the Application Popover View.</summary>
    /// <remarks>
    ///     <para>
    ///         To show or hide the Popover, set it's <see cref="View.Visible"/> property.
    ///     </para>
    /// </remarks>
    public static View? Popover

When set, if there's an Popover it's made Visible = false. Then the new View is set as the popover, initialized if needed.

A handler for _popover.VisibleChanged is added which does the heavy lifting.

To show a Popover, e.g. on a right mouse click, simply :

• Set your View's X/Y to the Screen-relative coords you want
• Set Application.Popover to your View
• Set yourView.Visible = true

        void TestFrameOnMouseClick (object sender, MouseEventArgs e)
        {
            if (e.Flags == MouseFlags.Button3Clicked)
            {
                popoverView.X = e.ScreenPosition.X;
                popoverView.Y = e.ScreenPosition.Y;
                Application.Popover = popoverView;
                Application.Popover!.Visible = true;
            }
        }

The View will remain visible and will prevent any other view from getting mouse/keyboard input until

• The user clicks outside of the popover's fame
• The user presses QuitKey
• Someone sets Applicaiton.Popover.Visible = false
• Someone sets a new View to Application.Popover

This works fairly brilliantly for:

Standalone use-cases as shown in ViewExperiments.cs

S

ContextMenu (hacked to use Menuv2/Bar - No sub-menus

Menuv (Prototype)

Problems

• It's really not a good design to couple more View logic in Application. I would really prefer that Application just knows about a single Top. This design actually works against what I'm trying to do with

  • Master Issue: Get rid of Toplevel - Introduce Runnable and Overlapped instead #2491

• MenuBar scenarios require the MenuBar, which is not a Popover, to still receive input when a sub-menu is shown as the Popo er. All modern menu systems, esp on Windows, let you hover over the menu bar once activated and sub-menus are automatcially shown/hidden as you do so:

With this design, there's no clean way to make this happen. Here's what it looks like now (I have to click on a menu bar item to activate it's submenu):

There's also no good way, with this design, to enable sub-menus.

I've spent a bunch of time noodling on this particular issue and tried several ideas, all of which seem like hacks and just cause more issues:

• Transform this._menuBar into a Popover dynamically (e.g.. clone it and set the clone to Application.Popover).
• Make Application.Popover be Stack<View> Popovers in conjunction with the clone idea.

So, for this reason, for now, I'm going to abandon this PR, fork the branch, and create a new PR that will try a different approach:

• Add ViewArrangement.Popover
• Any view with this flag set, will be "homed" from a layout/mouse/keyboard input perspective as though they were subviews of Application.Top