Fix Options dialog freezing when opening/closing multiple times

- Add _isInitialized flag to prevent multiple event subscriptions
- Skip re-initialization in FrmOptions_Load when form is reused
- Properly clean up Application.Idle handler in FormClosing
- Add test to verify form can be shown/hidden multiple times

Co-authored-by: Kvarkas <3611964+Kvarkas@users.noreply.github.com>

mRemoteNG/UI/Forms/frmOptions.cs

@@ -22,6 +22,7 @@ namespace mRemoteNG.UI.Forms
         private string _pageName;
         private readonly DisplayProperties _display = new();
         private readonly List<string> _optionPageObjectNames;
+        private bool _isInitialized = false;
 
         public FrmOptions() : this(Language.StartupExit)
         {
@@ -57,6 +58,13 @@ namespace mRemoteNG.UI.Forms
 
         private void FrmOptions_Load(object sender, EventArgs e)
         {
+            // Only initialize once to prevent multiple event subscriptions and page reloading
+            if (_isInitialized)
+            {
+                this.Visible = true;
+                return;
+            }
+
             this.Visible = true;
             FontOverrider.FontOverride(this);
             SetActivatedPage();
@@ -71,6 +79,7 @@ namespace mRemoteNG.UI.Forms
             //ThemeManager.getInstance().ThemeChanged += ApplyTheme;
             lstOptionPages.SelectedIndexChanged += LstOptionPages_SelectedIndexChanged;
             lstOptionPages.SelectedIndex = 0;
+            _isInitialized = true;
         }
 
         private void ApplyTheme()
@@ -274,6 +283,9 @@ namespace mRemoteNG.UI.Forms
 
         private void FrmOptions_FormClosing(object sender, FormClosingEventArgs e)
         {
+            // Ensure Application.Idle handler is removed if still attached
+            Application.Idle -= Application_Idle;
+            
             e.Cancel = true;
             this.Visible = false;
         }

mRemoteNGTests/UI/Forms/OptionsFormTests.cs

@@ -33,5 +33,32 @@ namespace mRemoteNGTests.UI.Forms
             ListViewTester listViewTester = new("lstOptionPages", _optionsForm);
             Assert.That(listViewTester.Items.Count, Is.EqualTo(12));
         }
+
+        [Test]
+        public void FormCanBeHiddenAndShownMultipleTimes()
+        {
+            // First show (already done in Setup)
+            Assert.That(_optionsForm.Visible, Is.True);
+            
+            // Hide the form
+            _optionsForm.Hide();
+            Assert.That(_optionsForm.Visible, Is.False);
+            
+            // Show it again
+            _optionsForm.Show();
+            Assert.That(_optionsForm.Visible, Is.True);
+            
+            // Verify pages are still loaded correctly
+            ListViewTester listViewTester = new("lstOptionPages", _optionsForm);
+            Assert.That(listViewTester.Items.Count, Is.EqualTo(12));
+            
+            // Hide and show one more time
+            _optionsForm.Hide();
+            _optionsForm.Show();
+            Assert.That(_optionsForm.Visible, Is.True);
+            
+            // Verify pages are still there
+            Assert.That(listViewTester.Items.Count, Is.EqualTo(12));
+        }
     }
 }