The coolDialog

MakeSomethingCool.ps1

function Show-MessageBox {
	param(
		$Title = "The cool Dialog",
		[Parameter(Mandatory=$true)]
		$Message,
		[System.Windows.Forms.MessageBoxIcon]$Icon = "Information",
		[System.Windows.Forms.MessageBoxButtons]$Buttons = "Ok"
	)
	[System.Windows.Forms.MessageBox]::Show($Message, $Title, $Buttons, $Icon) | Out-Null
}

try {
	$folderId = $vaultContext.CurrentSelectionSet | select -First 1 -ExpandProperty "Id"
	if(-not $folderId) { 
		throw "No valid folder selected!"
	}
	$fldr = $vault.DocumentService.GetFolderById($folderId)
	$folder = New-Object Autodesk.DataManagement.Client.Framework.Vault.Currency.Entities.Folder -ArgumentList @($vaultConnection, $fldr)

	[xml]$xamlContent = Get-Content "$($env:ProgramData)\Autodesk\Vault 2018\Extensions\DataStandard\Vault.Custom\addinVault\Menus\TheCoolDialog.xaml"
	$theCoolWindow = [Windows.Markup.XamlReader]::Load((New-Object System.Xml.XmlNodeReader -ArgumentList @($xamlContent)))

	$theCoolWindow.FindName("StackPanelCoolView").DataContext = $folder
	$theCoolWindow.FindName("BtnCool").add_Click({
		$coolUserInput = $theCoolWindow.FindName("TxtCoolInput").Text
		if($coolUserInput -notlike "*cool*") {
			Show-MessageBox -Message "Your input was not cool!`nTry it again!" -Icon "Warning"
		} else {
			@(@($theCoolWindow) + $theCoolWindow.FindName("StackPanelCoolView").Children + $theCoolWindow.FindName("StackPanelCoolBtns").Children) | where { $_.GetType() -ne [system.windows.controls.stackpanel] }  | foreach {
				$isTextBox = $_.GetType() -eq [system.windows.controls.TextBox]
				$_.BorderBrush = "White"
				$_.Background = if($isTextBox) { "LightGoldenrodYellow" } else { "Orange"}
				$_.Foreground = if($isTextBox) { "DarkOrange" } else { "White" }
			}
			Show-MessageBox -Message "Your input was $coolUserInput!"
		}
	})
	$theCoolWindow.FindName("BtnCancel").add_Click({
		$theCoolWindow.Close()
	})
	$theCoolWindow.ShowDialog() | Out-Null
} catch {
	$errorMessage = "Error message: '$($_.Exception.Message)'`n`n`nSTACKTRACE:`n$($_.InvocationInfo.PositionMessage)`n`n$($_.ScriptStacktrace)"
	Show-MessageBox -Message $errorMessage -Icon "Error"
}

MenuDefinitions.xml

<?xml version="1.0" encoding="utf-8"?>

<!--
Label: Label string for the command, must be quoted
Description: Description text for the menucommand. Must be quoted
Hint: Hint string, must be quoted
PSFile: Name of the *ps1 file that contains the powershell script to execute when the menu command is invoked, value must be quoted.
Image: Name of a bitmap file that contains the image for the menu command. Image should be 16x16 or 32x32, value must be quoted.
ToolbarPaintStyle: Controls how the item is drawn on toolbars, values are Text, Glyph, TextAndGlyph
NavigationTypes: comma separated list of entities for which this command should be active. Values are Bom, ChangeOrder, File, FileVersion, Folder, Item, Other
MultiSelectEnabled: If true, command is active for multiple selections, can be true or false
-->
<mymenu>
  <MenuItem>
    <NewTask Label="$UIString[MNU22]" Description="$UIString[MNU17]" Hint="$UIString[MNU18]"
             PSFile="CreateCustomObject.ps1" Image="NewCustomObject.ico" ToolbarPaintStyle="TextAndGlyph"
             NavigationTypes="Task" MultiSelectEnabled="False" />
    <EditTask Label="$UIString[MNU21]" Description="$UIString[MNU19]" Hint="$UIString[MNU20]"
              PSFile="EditCustomObject.ps1" Image="EditCustomObject.ico" ToolbarPaintStyle="TextAndGlyph"
              NavigationTypes="Task" MultiSelectEnabled="False" />
    <NewFile Label="$UIString[MNU1]" Description="$UIString[MNU11]" Hint="$UIString[MNU7]" PSFile="CreateFile.ps1"
             Image="NewStandardFile.ico" ToolbarPaintStyle="TextAndGlyph" NavigationTypes="File,Folder"
             MultiSelectEnabled="False" />
    <EditFile Label="$UIString[MNU2]" Description="$UIString[MNU12]" Hint="$UIString[MNU8]" PSFile="EditFile.ps1"
              Image="EditFileDatasheet.ico" ToolbarPaintStyle="TextAndGlyph" NavigationTypes="File"
              MultiSelectEnabled="False" />
    <NewFolder Label="$UIString[MNU3]" Description="$UIString[MNU13]" Hint="$UIString[MNU9]" PSFile="CreateFolder.ps1"
               Image="NewStandardFolder.ico" ToolbarPaintStyle="TextAndGlyph" NavigationTypes="Folder"
               MultiSelectEnabled="False" />
    <EditFolder Label="$UIString[MNU4]" Description="$UIString[MNU14]" Hint="$UIString[MNU10]" PSFile="EditFolder.ps1"
                Image="EditFolderDatasheet.ico" ToolbarPaintStyle="TextAndGlyph" NavigationTypes="Folder"
                MultiSelectEnabled="False" />
    <ShowLog Label="$UIString[MNU5]" Description="$UIString[MNU15]" Hint="$UIString[MNU5]" PSFile="ShowLog.ps1"
             Image="Log.ico" ToolbarPaintStyle="TextAndGlyph" MultiSelectEnabled="False" />
    <AboutDialog Label="$UIString[MNU6]" Description="$UIString[MNU16]" Hint="$UIString[MNU6]"
                 PSFile="ShowAboutDialog.ps1" Image="About.ico" ToolbarPaintStyle="TextAndGlyph"
                 MultiSelectEnabled="False" />
    <CoolDialog Label="Make something cool" Description="Lets be cool" Hint="'Cool'" PSFile="MakeSomethingCool.ps1" Image="coolOrange.ico" ToolbarPaintStyle="TextAndGlyph" NavigationTypes="Folder" MultiSelectEnabled="False" />
  </MenuItem>

  <!--
  Label:  String displayed as the label, e.g. for submenus, quoted
  DeployAsPulldown: If true, used as submenu, values are true or false
  Location: Specifies the location of the command site within the Vault CLient UI, values are
  StandardToolbar, AdvancedToolbar, BehaviorsToolbar, ItemBomToolbar,
  FileMenu, EditMenu, ActionsMenu, ToolsMenu, HelpMenu, FileContextMenu, FolderContextMenu, ChangeOrderContextMenu, ItemContextMenu
  Items: list with MenuItems. Name should be same as the element name defined in the MenuItem.
  -->

  <CommandSite>
    <FileContext Label="myMenu" DeployAsPullDown="False" Location="FileContextMenu">
      <Item Name="NewFile"></Item>
      <Item Name="EditFile"></Item>
    </FileContext>
    <FolderContex Label="myMenu" DeployAsPullDown="False" Location="FolderContextMenu">
      <Item Name="NewFile"></Item>
      <Item Name="NewFolder"></Item>
      <Item Name="EditFolder"></Item>
      <Item Name="CoolDialog"></Item>
    </FolderContex>
    <StandardToolbar Label="myMenu" DeployAsPullDown="False" Location="StandardToolbar">
      <Item Name="NewFile"></Item>
      <Item Name="EditFile"></Item>
    </StandardToolbar>
    <ToolsMenu Label="myMenu" DeployAsPullDown="False" Location="ToolsMenu">
      <Item Name="ShowLog"></Item>
    </ToolsMenu>
    <HelpMenu Label="myMenu" DeployAsPullDown="False" Location="HelpMenu">
      <Item Name="AboutDialog"></Item>
    </HelpMenu>
    <CustomObject Label="Task" DeployAsPullDown="False" Location="Task">
      <Item Name="NewTask"></Item>
      <Item Name="EditTask"></Item>
    </CustomObject>
  </CommandSite>

  <!--
  Comma separated list
  To suppress the command "New Library Folder" add the following two commands to the list below:
    NewLibraryFolder,NewLibraryFolderForContextMenus
  To suppress "Rename" for folder add this line:
    Folder.Rename
  -->
  <SuppressMenuItems>
    NewFolder,NewFolderGroupMenu,NewFolderGroupButton,NewFolderForContextMenus
  </SuppressMenuItems>
</mymenu>

TheCoolDialog.xaml

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
		xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
		xmlns:ig="http://schemas.infragistics.com/xaml"
		SizeToContent="WidthAndHeight"
		Title="The coolDialog"
		WindowStartupLocation="CenterScreen">
	<Window.Resources>
		<Style TargetType="{x:Type Button}">
			<Setter Property="Margin"
					Value="10" />
			<Setter Property="Height"
					Value="30" />
			<Setter Property="FontSize"
					Value="14" />
			<Setter Property="Width"
					Value="140" />
		</Style>
		<Style TargetType="{x:Type Label}">
			<Setter Property="FontSize"
					Value="12" />
		</Style>
		<Style TargetType="{x:Type TextBox}">
			<Setter Property="FontSize"
					Value="12" />
			<Setter Property="Height"
					Value="20" />
			<Setter Property="Margin"
					Value="5" />
		</Style>
	</Window.Resources>

	<StackPanel Name="StackPanelCoolView">
		<Label Content="Selected folder:" />
		<TextBox Text="{Binding Path=FullName, Mode=OneWay}"
				 IsReadOnly="True" />
		<Label Content="Insert a cool text:" />
		<TextBox Text="Type something cool" x:Name="TxtCoolInput" />

		<StackPanel Orientation="Horizontal" Name="StackPanelCoolBtns">
			<Button Content="Make something cool"
					TabIndex="1"
					x:Name="BtnCool" />
			<Button Content="Close"
					TabIndex="2"
					x:Name="BtnCancel" />
		</StackPanel>
	</StackPanel>
</Window>