Added better documentation

Actual README content
Upgraded to Unity 2020 LTS
Updated to reference new Core commit
Multiple styles added
More button examples added
Changed name of Test.cs - I guess Unity's reserved that class name now.
Added sample font

.gitignore

@@ -1,8 +1,12 @@
-.git
-.vs
-Library
-Logs
-obj
-Temp
-*.csproj
-*.sln
+.git
+.vs
+Library
+Logs
+obj
+Temp
+*.csproj
+*.sln
+.vsconfig
+
+Packages/packages-lock.json
+UserSettings

Assets/AppTest.cs

@@ -0,0 +1,302 @@
+// MIT License
+// 
+// Copyright (c) 2021 Pixel Precision, LLC
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+/// <summary>
+/// The demonstration script for the SampleScene example.
+/// </summary>
+public class AppTest : MonoBehaviour
+{
+    /// <summary>
+    /// The canvas to create the DropMenus in. Note that this
+    /// is also implied to be the Canvas that the RectTransforms
+    /// that we build the DropMenus around belong to.
+    /// </summary>
+    public Canvas canvas;
+
+    /// <summary>
+    /// Button for the "Simple Sample" example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample1;
+
+    /// <summary>
+    /// Button for the "Separated Sample" example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample2;
+
+    /// <summary>
+    /// Button for the "SubMenu Sample" example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample3;
+
+    /// <summary>
+    /// Button for the "Deeper SubMenu example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample4;
+
+    /// <summary>
+    /// Button for the "Tall Scrollable" example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample5;
+
+    /// <summary>
+    /// Button for the "README Sample" example.
+    /// </summary>
+    public UnityEngine.UI.Button btn_Sample6;
+
+    /// <summary>
+    /// A green dot used as an example for the style pulldown, to show
+    /// decorating a (selected) menu item with a sprite.
+    /// </summary>
+    public Sprite greenDot;
+
+    /// <summary>
+    /// The "Simple" example that can be selected from the style pulldown.
+    /// </summary>
+    public PxPre.DropMenu.Props prop_Simple;
+
+    /// <summary>
+    /// The "Skeuo" example that can be selected from the style pulldown.
+    /// </summary>
+    public PxPre.DropMenu.Props prop_Skeuo;
+
+    /// <summary>
+    /// The button for the style pulldown example. This is a button that 
+    /// emulates a pulldown, and allows changing the property style that
+    /// the DropMenus will use when invoked.
+    /// </summary>
+    public UnityEngine.UI.Button btn_StylePulldown;
+
+    /// <summary>
+    /// The text field for the style pulldown button.
+    /// </summary>
+    public UnityEngine.UI.Text txt_StyleName;
+
+    /// <summary>
+    /// A sample parameter-less function.
+    /// </summary>
+    public void FunctionAction()
+    {
+        Debug.Log("Ran FunctionAction()");
+    }
+
+    /// <summary>
+    /// Button callback for the "Simple Sample" button.
+    /// 
+    /// An example of creating a simple dropdown.
+    /// </summary>
+    public void OnButton_SimpleSample()
+    {
+        Debug.Log("Called OnButton_SimpleSample()");
+
+        // The button to create a menu dropdown onto
+        RectTransform rt = this.btn_Sample1.GetComponent<RectTransform>();
+
+        // This creates a PxPre.DropMenu.Node object, wrapped in a
+        // PxPre.DropMenu.StackUtil object that provides API members to
+        // easily populate the menu.
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        // Add a menu option to the menu.
+        menuStack.AddAction("Function Action", this.FunctionAction);
+
+        // Create the popup around the RectTransform of btn_Sample1. 
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    /// <summary>
+    /// Button callback for the "Separated Sample" button.
+    /// 
+    /// An example of using the AddSeparator() function to add a 
+    /// horizontal rule between menu items.
+    /// </summary>
+    public void OnButton_SeparatedSample()
+    {
+        Debug.Log("Called OnButton_SeparatedSample()");
+
+        RectTransform rt = this.btn_Sample2.GetComponent<RectTransform>();
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        // Similar to OnButton_SimpleSample() except multiple items are added
+        // to menuStack, including a separator in between.
+        menuStack.AddAction("Option 1", ()=>{ Debug.Log("Lambda for Option 1"); });
+        menuStack.AddSeparator();
+        menuStack.AddAction("Below Separator", () => { Debug.Log("Lambda for Below Separator"); });
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    /// <summary>
+    /// Button callback for the "SubMenu Sample" button.
+    /// 
+    /// An example of creating cascading submenus.
+    /// </summary>
+    public void OnButton_SubMenu()
+    {
+        Debug.Log("Called OnButton_SubMenu()");
+
+        // The button to create a menu dropdown onto
+        RectTransform rt = this.btn_Sample3.GetComponent<RectTransform>();
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        // Setting the action to lambda buttons
+        menuStack.AddAction("Option 1", () => { Debug.Log("Lambda for Option 1"); });
+        menuStack.AddAction("Option 2", () => { Debug.Log("Lambda for Option 2"); });
+
+        // Setting the action to parameterless (member) functions
+        menuStack.PushMenu("Pushed Sub Menu");
+            menuStack.AddAction("Option 3", this.FunctionAction);
+            menuStack.AddAction("Option 4", this.FunctionAction);
+            menuStack.AddAction("Option 5", this.FunctionAction);
+        menuStack.PopMenu();
+
+        menuStack.AddAction("Option 6", () => { });
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    /// <summary>
+    /// Button callback for the "Deeper SubMenu" button.
+    /// 
+    /// An extended example of cascading submenus, with multiple 
+    /// depths of submenus.
+    /// </summary>
+    public void OnButton_DeeperSubMenu()
+    {
+        Debug.Log("Called OnButton_DeeperSubMenu()");
+
+        // The button to create a menu dropdown onto
+        RectTransform rt = this.btn_Sample4.GetComponent<RectTransform>();
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        menuStack.PushMenu("Pushed Sub Menu (1)");
+            menuStack.AddAction("Option 1", () => { });
+            menuStack.PushMenu("Pushed Sub Menu (2)");
+                menuStack.AddAction("Option 2", () => { });
+                menuStack.AddAction("Option 3", () => { });
+            menuStack.PopMenu();
+            menuStack.AddAction("Option 4", () => { });
+        menuStack.PopMenu();
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    /// <summary>
+    /// Button callback for the "Tall Scrollable" button.
+    /// </summary>
+    public void OnButton_TallScrollable()
+    {
+        Debug.Log("Called OnButton_TallScrollable()");
+
+        // The button to create a menu dropdown onto
+        RectTransform rt = this.btn_Sample5.GetComponent<RectTransform>();
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        // Create a lot of (do nothing) menu items so a vertical scrollbar will be needed.
+        for(int i = 0; i < 100; ++i)
+            menuStack.AddAction($"Option {i}", () => { }); 
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    void OnMenu_Option2()
+    { 
+        Debug.Log("Called OnMenu_Option2");
+    }
+
+    /// <summary>
+    /// Button callback for the "README Sample" button.
+    /// </summary>
+    public void OnButton_READMESample()
+    {
+        Debug.Log("Called OnButton_READMESample()");
+
+        RectTransform rt = this.btn_Sample6.GetComponent<RectTransform>();
+
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        menuStack.AddAction("Option 1", () => { Debug.Log("Called Option 1"); });
+        menuStack.AddAction("Option 2", this.OnMenu_Option2);
+
+        menuStack.AddSeparator();
+
+        menuStack.PushMenu("Submenu");
+        for (int i = 0; i < 10; ++i)
+        {
+            int iCpy = i; // The for loop iterator value cannot be used directly.
+            menuStack.AddAction($"SubSubOpt {iCpy}", () => { Debug.Log(iCpy.ToString()); });
+        }
+        menuStack.PopMenu();
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(
+            this.canvas,
+            menuStack.Root,
+            rt);
+    }
+
+    /// <summary>
+    /// Button callback for the style change pulldown button.
+    /// </summary>
+    public void OnButton_StylePulldown()
+    {
+        Debug.Log("Called OnButton_StylePulldown()");
+
+        PxPre.DropMenu.Props curProp = PxPre.DropMenu.DropMenuSingleton.MenuInst.props;
+
+        RectTransform rt = this.btn_StylePulldown.GetComponent<RectTransform>();
+        PxPre.DropMenu.StackUtil menuStack = new PxPre.DropMenu.StackUtil("");
+
+        menuStack.AddAction(
+            curProp == this.prop_Simple,                            // Is menu item selected?
+            curProp == this.prop_Simple ? this.greenDot : null,     // If selected, decorate with lead green dot sprite
+            "Simple",
+            () => { this.SetStyle(this.prop_Simple); });
+
+        menuStack.AddAction(
+            curProp == this.prop_Skeuo,                             // Is menu item selected?
+            curProp == this.prop_Skeuo ? this.greenDot : null,      // If selected, decorate with lead green dot sprite
+            "Skeuo", 
+            () => { this.SetStyle(this.prop_Skeuo); });
+
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.CreateDropdownMenu(this.canvas, menuStack.Root, rt);
+    }
+
+    /// <summary>
+    /// DropMenu callback for the menu items in OnButton_StylePulldown().
+    /// 
+    /// This will set the stylesheet Prop that all future invoked
+    /// DropMenus will use.
+    /// </summary>
+    /// <param name="p">The property to set.</param>
+    public void SetStyle(PxPre.DropMenu.Props p)
+    {
+        PxPre.DropMenu.DropMenuSingleton.MenuInst.props = p;
+
+        if (p == this.prop_Simple)
+            this.txt_StyleName.text = "Style: Simple";
+        else
+            this.txt_StyleName.text = "Style: Skeuo";
+    }
+}