Read up/down keys on *nix properly - fixes #11

Related issues:
- PowerShell/PowerShell#16443
- dotnet/runtime#63387
- PowerShell/PowerShell#16606

PSMenu/Private/Read-VKey.ps1

@@ -3,6 +3,31 @@ function Read-VKey() {
     $ErrMsg = "Current host '$CurrentHost' does not support operation 'ReadKey'"
 
     try {
+         # Issues with reading up and down arrow keys
+         # - https://github.com/PowerShell/PowerShell/issues/16443
+         # - https://github.com/dotnet/runtime/issues/63387
+         # - https://github.com/PowerShell/PowerShell/issues/16606
+         if ($IsLinux -or $IsMacOS) {
+            ## A bug with Linux and Mac where arrow keys are return in 2 chars.  First is esc follow by A,B,C,D
+            $key1 = $CurrentHost.UI.RawUI.ReadKey("NoEcho,IncludeKeyDown")
+
+            if ($key1.VirtualKeyCode -eq 0x1B) {
+               ## Found that we got an esc chair so we need to grab one more char
+               $key2 = $CurrentHost.UI.RawUI.ReadKey("NoEcho,IncludeKeyDown")
+
+               ## We just care about up and down arrow mapping here for now.
+                if ($key2.VirtualKeyCode -eq 0x41) {
+                    # VK_UP = 0x26 up-arrow
+                    $key1.VirtualKeyCode = 0x26
+                }
+                if ($key2.VirtualKeyCode -eq 0x42) {
+                    # VK_DOWN = 0x28 down-arrow
+                    $key1.VirtualKeyCode = 0x28
+                }
+            }
+            Return $key1
+        }
+
         Return $CurrentHost.UI.RawUI.ReadKey("NoEcho,IncludeKeyDown")
     }
     catch [System.NotSupportedException] {