diff --git a/Src/Common/Controls/DetailControls/ChooserCommand.cs b/Src/Common/Controls/DetailControls/ChooserCommand.cs
index 388b37b707..16f0a3bf57 100644
--- a/Src/Common/Controls/DetailControls/ChooserCommand.cs
+++ b/Src/Common/Controls/DetailControls/ChooserCommand.cs
@@ -5,14 +5,12 @@
 using System;
 using System.Windows.Forms;
 using System.Linq;
-using SIL.LCModel.Core.Text;
 using SIL.FieldWorks.Common.Framework.DetailControls.Resources;
 using SIL.LCModel;
 using SIL.LCModel.DomainServices;
 using SIL.LCModel.Infrastructure;
 using SIL.FieldWorks.LexText.Controls;
 using SIL.FieldWorks.Common.Controls;
-using SIL.FieldWorks.Common.FwUtils;
 using XCore;
 
 namespace SIL.FieldWorks.Common.Framework.DetailControls
@@ -47,7 +45,7 @@ public override ObjectLabel Execute()
 				dlg.SetDlgInfo(m_cache, morphType, MsaType.kInfl, m_slot, m_mediator, m_propertyTable,
 					m_fPrefix ? InsertEntryDlg.MorphTypeFilterType.Prefix : InsertEntryDlg.MorphTypeFilterType.Suffix);
 				dlg.DisableAffixTypeMainPosAndSlot();
-				if (dlg.ShowDialog() == DialogResult.OK)
+				if (dlg.ShowDialog(m_propertyTable.GetValue<Form>("window")) == DialogResult.OK)
 				{
 					bool fCreated;
 					ILexEntry entry;
diff --git a/Src/FwCoreDlgs/FwCoreDlgsTests/FwNewLangProjectModelTests.cs b/Src/FwCoreDlgs/FwCoreDlgsTests/FwNewLangProjectModelTests.cs
index 190eacf271..961be65d8e 100644
--- a/Src/FwCoreDlgs/FwCoreDlgsTests/FwNewLangProjectModelTests.cs
+++ b/Src/FwCoreDlgs/FwCoreDlgsTests/FwNewLangProjectModelTests.cs
@@ -106,6 +106,8 @@ public void FwNewLangProjectModel_VerifyCreateNewLangProject()
 		[TestCase("*", false)]
 		[TestCase("franç", false)] // upper ASCII is forbidden
 		[TestCase("\u0344", false)] // non-ASCII is forbidden
+		[TestCase("MyProject ", true)] // trailing space is trimmed, still valid (LT-22578)
+		[TestCase("   ", false)] // whitespace-only trims to empty -> invalid (LT-22578)
 		public void FwNewLangProjectModel_ProjectNameIsValid(string projName, bool expectedResult)
 		{
 			var testModel = new FwNewLangProjectModel
@@ -116,6 +118,25 @@ public void FwNewLangProjectModel_ProjectNameIsValid(string projName, bool expec
 			Assert.That(testModel.IsProjectNameValid, Is.EqualTo(expectedResult));
 		}
 
+		/// <summary>
+		/// The name is trimmed of surrounding whitespace when stored, so the validated name matches
+		/// the name used to create the project directory. Windows strips trailing spaces/dots from
+		/// folder names, so an untrimmed name crashes on creation (LT-22578).
+		/// </summary>
+		[TestCase("MyProject ", "MyProject", TestName = "TrailingSpace")]
+		[TestCase(" MyProject", "MyProject", TestName = "LeadingSpace")]
+		[TestCase("  MyProject  ", "MyProject", TestName = "SurroundingSpace")]
+		[TestCase("My Project", "My Project", TestName = "InteriorSpacePreserved")]
+		public void FwNewLangProjectModel_ProjectName_TrimsSurroundingWhitespace(string input, string expected)
+		{
+			var testModel = new FwNewLangProjectModel
+			{
+				LoadProjectNameSetup = () => { },
+				ProjectName = input
+			};
+			Assert.That(testModel.ProjectName, Is.EqualTo(expected));
+		}
+
 		/// <summary/>
 		[Test]
 		public void FwNewLangProjectModel_ProjectNameIsUnique()
diff --git a/Src/FwCoreDlgs/FwNewLangProjectModel.cs b/Src/FwCoreDlgs/FwNewLangProjectModel.cs
index c7a06241b6..624f3e53c5 100644
--- a/Src/FwCoreDlgs/FwNewLangProjectModel.cs
+++ b/Src/FwCoreDlgs/FwNewLangProjectModel.cs
@@ -208,7 +208,7 @@ public string ProjectName
 			get { return _projectName; }
 			set
 			{
-				_projectName = value;
+				_projectName = value?.Trim();
 				_steps[(int)CurrentStep].IsComplete = IsProjectNameValid;
 				LoadProjectNameSetup();
 			}
diff --git a/Src/LexText/Morphology/InflAffixTemplateControl.cs b/Src/LexText/Morphology/InflAffixTemplateControl.cs
index 2d3a90bb0b..d6bdce81a8 100644
--- a/Src/LexText/Morphology/InflAffixTemplateControl.cs
+++ b/Src/LexText/Morphology/InflAffixTemplateControl.cs
@@ -412,7 +412,7 @@ public bool OnInflTemplateAddInflAffixMsa(object cmd)
 
 			using (var chooser = MakeChooserWithExtantMsas(m_slot, cmd as XCore.Command))
 			{
-				chooser.ShowDialog();
+				chooser.ShowDialog(this);
 				if (chooser.DialogResult == DialogResult.OK)
 				{
 					if (chooser.ChosenObjects != null && chooser.ChosenObjects.Count() > 0)