Error when using winform with C#

Please help me :((
When using winform, after executing the function. NX always displays the message board: Work in process, Click stop to interput this operator.
How does NX finish after function execution?

Code: Event click to table, select face change color.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;

using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using NXOpen;
using NXOpenUI;

namespace ColorTable
{
static class Program
{
///
/// The main entry point for the application.
///
[STAThread]
public static void Main(string[] args)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
public static int GetUnloadOption(string dummy)
{ return (int)NXOpen.Session.LibraryUnloadOption.Immediately; }
}

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

List mySelectedObjects = new List();

public static Selection.Response SelectmultiObkjects(string prompt, ref List dispObj )
{
TaggedObject[] selObj;
UI theUI = UI.GetUI();
string title = "Select face";
Selection.SelectionAction selAction = Selection.SelectionAction.ClearAndEnableSpecific;
Selection.SelectionScope scope = Selection.SelectionScope.AnyInAssembly;
Selection.MaskTriple[] selectionMask_array = new Selection.MaskTriple[1];
selectionMask_array[0].Type = NXOpen.UF.UFConstants.UF_face_type;
selectionMask_array[0].SolidBodySubtype = NXOpen.UF.UFConstants.UF_UI_SEL_FEATURE_SOLID_BODY;

Selection.Response resp = theUI.SelectionManager.SelectTaggedObjects(prompt, title, scope, selAction, false, false, selectionMask_array, out selObj);

if(resp == Selection.Response.ObjectSelected || resp == Selection.Response.ObjectSelectedByName || resp == Selection.Response.Ok)
{
foreach(NXObject item in selObj)
{
dispObj.Add((NXOpen.DisplayableObject)item);
}
return Selection.Response.Ok;
}
else
{
return Selection.Response.Cancel;
}
}

private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
Session theSession = Session.GetSession();
Part workPart = theSession.Parts.Work;
Part displayPart = theSession.Parts.Display;

UI theUI = UI.GetUI();

if(SelectmultiObkjects("Color Table (Code by Mold CADCAM P)", ref mySelectedObjects) == Selection.Response.Ok)
{
NXOpen.DisplayModification displayModification1;

displayModification1 = theSession.DisplayManager.NewDisplayModification();

displayModification1.ApplyToAllFaces = true;

displayModification1.ApplyToOwningParts = true;

displayModification1.NewColor = 186;

displayModification1.Apply(mySelectedObjects.ToArray());

displayModification1.Dispose();

}
}
}

partial class Form1
{
///
/// Required designer variable.
///
private System.ComponentModel.IContainer components = null;

///
/// Clean up any resources being used.
///
/// true if managed resources should be disposed; otherwise, false.
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}

#region Windows Form Designer generated code

///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///
private void InitializeComponent()
{
System.Windows.Forms.ListViewItem listViewItem1 = new System.Windows.Forms.ListViewItem(new System.Windows.Forms.ListViewItem.ListViewSubItem[] {
new System.Windows.Forms.ListViewItem.ListViewSubItem(null, "91"),
new System.Windows.Forms.ListViewItem.ListViewSubItem(null, "", System.Drawing.SystemColors.WindowText, System.Drawing.Color.Blue, new System.Drawing.Font("Microsoft Sans Serif", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0))))}, -1);
this.listView1 = new System.Windows.Forms.ListView();
this.columnHeader1 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
this.columnHeader2 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
this.columnHeader3 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
this.SuspendLayout();
//
// listView1
//
this.listView1.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
this.columnHeader1,
this.columnHeader2,
this.columnHeader3});
this.listView1.FullRowSelect = true;
this.listView1.GridLines = true;
this.listView1.Items.AddRange(new System.Windows.Forms.ListViewItem[] {
listViewItem1});
this.listView1.Location = new System.Drawing.Point(-1, 2);
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(599, 507);
this.listView1.TabIndex = 0;
this.listView1.UseCompatibleStateImageBehavior = false;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.SelectedIndexChanged += new System.EventHandler(this.listView1_SelectedIndexChanged);
//
// columnHeader1
//
this.columnHeader1.Text = "Code";
//
// columnHeader2
//
this.columnHeader2.Text = "Color";
this.columnHeader2.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
this.columnHeader2.Width = 80;
//
// columnHeader3
//
this.columnHeader3.Text = "Tolerance";
this.columnHeader3.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
this.columnHeader3.Width = 151;
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(739, 501);
this.Controls.Add(this.listView1);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);

}

#endregion

private System.Windows.Forms.ListView listView1;
private System.Windows.Forms.ColumnHeader columnHeader1;
private System.Windows.Forms.ColumnHeader columnHeader2;
private System.Windows.Forms.ColumnHeader columnHeader3;
}

}