The quick answer

Using the Extended ASCII code, Alt + <Char#> - Note that the Char# is typed by using the Number Pad when 'Num Lock' is on:

┌────┐┌────┐┌────┐┌────┐
│Num ││ /  ││ *  ││ -  │
│Lock││    ││    ││    │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 7  ││ 8  ││ 9  ││ +  │
│Home││ ↑  ││PgDn││    │
└────┘└────┘└────┘│    │
┌────┐┌────┐┌────┐│    │
│ 4  ││ 5  ││ 6  ││    │
│←   ││    ││   →││    │
└────┘└────┘└────┘└────┘
┌────┐┌────┐┌────┐┌────┐
│ 1  ││ 2  ││ 3  ││ <─┘│
│End ││ ↓  ││PgDn││    │
└────┘└────┘└────┘│    │
┌──────────┐┌────┐│    │
│ 0        ││ .  ││    │
│Ins       ││Del ││    │
└──────────┘└────┘└────┘

For example:

1. Extended Ascii: Alt+218='┌', Alt+196='─', Alt+194='┬', Alt+191='┐', Alt+195='├', Alt+197='┼', Alt+180='┤', Alt+192='└', Alt+193='┴', Alt+217='┘'...
   You can find this table in:
2. Unicode: Alt+8592='←', Alt+8593='↑', Alt+8594='→', Alt+8595='↓',

Note that Number Pad above is created using these example characters.

The Specific Example

//
// This is a dialog that can run a specific program requested by the user.
// It looks like:
// ┌────────────────────────────────────────────────────────────────────┐
// │ [icon] Run                                                      [X]│
// ├────────────────────────────────────────────────────────────────────┤
// │                                                                    │
// │ ┌big ┐ Type the name of a program, folder, document, or Internet   │
// │ └icon┘ resource, and Windows will open it for you.                 │
// │                                                                    │
// │       ┌────────────────────────────────────────────────────────┬─┐ │
// │ Open: │<File Name/FilePath>                                    │▼│ │
// │       └────────────────────────────────────────────────────────┴─┘ │
// ├────────────────────────────────────────────────────────────────────┤
// │                               ┌──────────┐┌──────────┐┌──────────┐ │
// │                               │    OK    ││  Cancel  ││  Browse… │ │
// │                               └──────────┘└──────────┘└──────────┘ │
// └────────────────────────────────────────────────────────────────────┘
//
// It functional parts are:
// the 'Open' drop down text box, 'X' window button, 'OK', 'Cancel' and 'Browse...' buttons.
//
// The drop down text box is filled by: 
// 1. Keeping the last run item.
// 2. Typing manually the program the user wants to activate.
// 3. Clicking on the drop down arrow to select previously run item.
// 4. Clicking on the 'Browse...' button to look for the run item file.
//    this will open the file dialog and will show files that have the 
//    '.exe', '.pif', '.com', '.bat' and '.cmd' extension.
//
// Program Running: 
// 1. The program is run when either clicking on the 'Ok' button or 
//    pressing the 'enter' on the keyboard when the drop down text box 
//    is active. 
// 2. When ever the item is not a full path item, the program uses the
//    system search path. With the the above extensions to find it and
//    run it.
// 3. If the program can`t be run an OK message is shown, Clicking on 
//    the 'Ok' button will go back to the run dialog focusing and  
//    selecting on the 'Open' Drop Down Text Box:
//    ┌──────────────────────────────────────────────────────────────────────────────────┐
//    │ [icon] Run                                                                    [X]│
//    ├──────────────────────────────────────────────────────────────────────────────────┤
//    │                                                                                  │
//    │ ┌big ┐ Windows cannot find '<Wong Name>'. Make sure you typed the name correctly,│
//    │ └icon┘ and then try again.                                                       │
//    │                                                                                  │
//    ├──────────────────────────────────────────────────────────────────────────────────┤
//    │                                                                     ┌──────────┐ │
//    │                                                                     │    OK    │ │
//    │                                                                     └──────────┘ │
//    └──────────────────────────────────────────────────────────────────────────────────┘
//
// The run is canceled by either clicking on the 'Cancel' button or 
// the 'X' window button.
// 
// When the dialog is opened the 'Open' drop down text box is in focus 
// and the last Run item is selected.
// 
// The order of keyboard Tab clicking is: 'Open' Drop Down Text Box -> 
// 'OK' Button -> 'Cancel' Button -> 'Browse..'
//
// Key Board Short Cuts: 
// 1. Alt+O - to focus and select the 'Open' Drop Down Text Box.
// 2. Alt+B - to open the 'Browse..' file dialog.
//

Back Ground

In the late 80th when I was in high school I had a project in Cobol (god forbid ;) ), me and my class mates had to put there explanations, for the UI. Actually the UI itself looked like this, for this we used the extended ASCII code (128...255) char codes - no Unicode back at that time).

Links

1. Ascii Table: https://psy.swan.ac.uk/staff/carter/Vim/vim_ascii_chars.htm (for ♥♦♣♠↑↓→←▲▼►◄... chracters)

2. Extended Ascii Table: https://www.webopedia.com/definitions/extended-ascii/

3. Code Example with comments I posted here several years ago: https://stackoverflow.com/a/61776670/10571377\*

*This self posted question was due to a comment i got on my answer.