Fix LT-22578: dialog window Z order issues

Src/Common/Controls/DetailControls/ChooserCommand.cs

@@ -33,6 +33,15 @@ public MakeInflAffixEntryChooserCommand(LcmCache cache, bool fCloseBeforeExecuti
 			m_slot = slot;
 		}
 
+		/// <summary>
+		/// This command opens the modal New Entry dialog, so have the chooser keep the main window
+		/// active as it hides, to avoid another application flashing in front first.
+		/// </summary>
+		public override bool KeepOwnerActiveWhenHiding
+		{
+			get { return true; }
+		}
+
 		//methods
 
 		public override ObjectLabel Execute()

Src/Common/Controls/DetailControls/DetailControlsTests/ChooserCommandKeepOwnerActiveWhenHidingTests.cs

@@ -0,0 +1,44 @@
+// Copyright (c) 2026 SIL International
+// This software is licensed under the LGPL, version 2.1 or later
+// (http://www.gnu.org/licenses/lgpl-2.1.html)
+
+using NUnit.Framework;
+
+namespace SIL.FieldWorks.Common.Framework.DetailControls
+{
+	/// <summary>
+	/// Guards the KeepOwnerActiveWhenHiding opt-in contract for the affix chooser commands
+	/// (LT-22578). A chooser command whose Execute() opens another modal dialog must return true
+	/// so ReallySimpleListChooser.HideForCommand re-activates the FLEx main window as the chooser
+	/// hides; without it an unrelated application can flash in front while the new dialog loads. A
+	/// command that opens no dialog must stay false (the base default). The flag is the only part
+	/// of the fix that is deterministic and UI-free; the actual owner activation and window
+	/// Z-order require a live message pump and are verified manually.
+	/// </summary>
+	[TestFixture]
+	public class ChooserCommandKeepOwnerActiveWhenHidingTests
+	{
+		/// <summary>
+		/// Opens the modal New Entry dialog (InsertEntryDlg), so it must opt in.
+		/// </summary>
+		[Test]
+		public void MakeInflAffixEntryChooserCommand_OptsIn()
+		{
+			var command = new MakeInflAffixEntryChooserCommand(
+				null, true, "label", true, null, null, null);
+			Assert.That(command.KeepOwnerActiveWhenHiding, Is.True);
+		}
+
+		/// <summary>
+		/// Creates a slot without opening a dialog, so it keeps the base default of false. This
+		/// also exercises the base ChooserCommand default (this command does not override it).
+		/// </summary>
+		[Test]
+		public void MakeInflAffixSlotChooserCommand_DoesNotOptIn()
+		{
+			var command = new MakeInflAffixSlotChooserCommand(
+				null, true, "label", 0, false, null, null);
+			Assert.That(command.KeepOwnerActiveWhenHiding, Is.False);
+		}
+	}
+}

Src/Common/Controls/XMLViews/ChooserCommandBase.cs

@@ -97,6 +97,20 @@ public bool ShouldCloseBeforeExecuting
 				m_fShouldCloseBeforeExecuting = value;
 			}
 		}
+
+		/// <summary>
+		/// When true, the chooser re-enables its owner window just before hiding itself to run this
+		/// command. Execute() for such a command opens another modal dialog, which re-disables the
+		/// owner; re-enabling it first makes the OS return activation to the FLEx main window when
+		/// the chooser hides, instead of momentarily revealing an unrelated application's window.
+		/// Defaults to false so behavior is unchanged for every command that does not opt in. See
+		/// the "Create new inflectional affix" flow (LT-22578).
+		/// </summary>
+		public virtual bool KeepOwnerActiveWhenHiding
+		{
+			get { return false; }
+		}
+
 		/// <summary>
 		/// The entire text of the label that will appear in the chooser
 		/// </summary>

Src/Common/Controls/XMLViews/ReallySimpleListChooser.cs

@@ -2281,6 +2281,27 @@ private void InitializeComponent()
 		}
 		#endregion
 
+		/// <summary>
+		/// Hide the chooser before running <paramref name="cmd"/>. When the command opts in via
+		/// KeepOwnerActiveWhenHiding (its Execute() opens another modal dialog), re-enable and then
+		/// re-activate our owner around the hide. While the chooser is modal the OS has disabled the
+		/// owner, so hiding alone would hand the foreground to another application (the next window
+		/// by z-order) instead of back to the FLEx main window, causing a brief flash. Re-enabling is
+		/// not enough on its own; the Activate() is what pulls FLEx forward, and it is not blocked by
+		/// the foreground lock because we are still the foreground process here (LT-22578).
+		/// </summary>
+		private void HideForCommand(ChooserCommand cmd)
+		{
+			if (cmd != null && cmd.KeepOwnerActiveWhenHiding && Owner != null)
+			{
+				Owner.Enabled = true;
+				Visible = false;
+				Owner.Activate();
+				return;
+			}
+			Visible = false;
+		}
+
 		private void HandleCommmandChoice(ChooserCommandNode node)
 		{
 			if (node != null)
@@ -2289,7 +2310,7 @@ private void HandleCommmandChoice(ChooserCommandNode node)
 				if (cmd != null)
 				{
 					if (cmd.ShouldCloseBeforeExecuting)
-						Visible = false;
+						HideForCommand(cmd);
 					m_chosenLabel = cmd.Execute();
 				}
 			}
@@ -2300,7 +2321,7 @@ private void OnOKClick(object sender, EventArgs e)
 			Persist();
 			if (m_linkCmd != null)
 			{
-				Visible = false;
+				HideForCommand(m_linkCmd);
 				m_chosenLabel = m_linkCmd.Execute();
 				m_fLinkExecuted = true;
 			}

Src/LexText/Lexicon/EntrySequenceReferenceLauncher.cs

@@ -126,7 +126,7 @@ protected override void HandleChooser()
 					chooser.InitializeExtras(null, Mediator, m_propertyTable);
 					chooser.AddLink(LexEdStrings.ksAddAComponent, ReallySimpleListChooser.LinkType.kDialogLink,
 						new AddPrimaryLexemeChooserCommand(m_cache, false, null, m_mediator, m_propertyTable, m_obj, FindForm()));
-					DialogResult res = chooser.ShowDialog();
+					DialogResult res = chooser.ShowDialog(FindForm());
 					if (DialogResult.Cancel == res)
 						return;
 					if (chooser.ChosenObjects != null)
@@ -204,7 +204,7 @@ private void HandleChooserForBackRefs(string fieldName, bool fPropContainsEntryR
 				// Step 3 of LT-11155:
 				chooser.AddLink(LexEdStrings.ksAddAComplexForm, ReallySimpleListChooser.LinkType.kDialogLink,
 					new AddComplexFormChooserCommand(m_cache, false, null, m_mediator, m_propertyTable, m_obj, FindForm()));
-				DialogResult res = chooser.ShowDialog();
+				DialogResult res = chooser.ShowDialog(FindForm());
 				if (DialogResult.Cancel == res)
 					return;
 				var chosenObjects = chooser.ChosenObjects;
@@ -353,6 +353,15 @@ public AddPrimaryLexemeChooserCommand(LcmCache cache, bool fCloseBeforeExecuting
 			m_parentWindow = parentWindow;
 		}
 
+		/// <summary>
+		/// This command opens the modal LinkEntryOrSenseDlg, so have the chooser keep the main
+		/// window active as it hides, to avoid another application flashing in front first.
+		/// </summary>
+		public override bool KeepOwnerActiveWhenHiding
+		{
+			get { return true; }
+		}
+
 		public override ObjectLabel Execute()
 		{
 			ObjectLabel result = null;
@@ -426,6 +435,15 @@ public AddComplexFormChooserCommand(LcmCache cache, bool fCloseBeforeExecuting,
 			m_parentWindow = parentWindow;
 		}
 
+		/// <summary>
+		/// This command opens the modal EntryGoDlg, so have the chooser keep the main window
+		/// active as it hides, to avoid another application flashing in front first.
+		/// </summary>
+		public override bool KeepOwnerActiveWhenHiding
+		{
+			get { return true; }
+		}
+
 		public override ObjectLabel Execute()
 		{
 			ObjectLabel result = null;

Src/LexText/Lexicon/LexEdDllTests/EntrySequenceChooserCommandKeepOwnerActiveWhenHidingTests.cs

@@ -0,0 +1,43 @@
+// Copyright (c) 2026 SIL International
+// This software is licensed under the LGPL, version 2.1 or later
+// (http://www.gnu.org/licenses/lgpl-2.1.html)
+
+using NUnit.Framework;
+using SIL.FieldWorks.XWorks.LexEd;
+
+namespace LexEdDllTests
+{
+	/// <summary>
+	/// Guards the KeepOwnerActiveWhenHiding opt-in contract for the Lexicon "Add a Component" and
+	/// "Add a Complex Form" chooser commands (LT-22578). Both are launched from a chooser that
+	/// hides itself and then open a modal dialog (LinkEntryOrSenseDlg / EntryGoDlg), so both must
+	/// opt in to keep an unrelated application from flashing in front while the dialog loads. See
+	/// ChooserCommandKeepOwnerActiveWhenHidingTests (DetailControls) for the affix equivalents and
+	/// the rationale for why only the opt-in flag is unit-tested.
+	/// </summary>
+	[TestFixture]
+	public class EntrySequenceChooserCommandKeepOwnerActiveWhenHidingTests
+	{
+		/// <summary>
+		/// "Add a Component" opens the modal LinkEntryOrSenseDlg, so it must opt in.
+		/// </summary>
+		[Test]
+		public void AddPrimaryLexemeChooserCommand_OptsIn()
+		{
+			var command = new AddPrimaryLexemeChooserCommand(
+				null, false, "label", null, null, null, null);
+			Assert.That(command.KeepOwnerActiveWhenHiding, Is.True);
+		}
+
+		/// <summary>
+		/// "Add a Complex Form" opens the modal EntryGoDlg, so it must opt in.
+		/// </summary>
+		[Test]
+		public void AddComplexFormChooserCommand_OptsIn()
+		{
+			var command = new AddComplexFormChooserCommand(
+				null, false, "label", null, null, null, null);
+			Assert.That(command.KeepOwnerActiveWhenHiding, Is.True);
+		}
+	}
+}

Src/LexText/Morphology/InflAffixTemplateControl.cs

@@ -412,7 +412,8 @@ public bool OnInflTemplateAddInflAffixMsa(object cmd)
 
 			using (var chooser = MakeChooserWithExtantMsas(m_slot, cmd as XCore.Command))
 			{
-				chooser.ShowDialog(this);
+				// Own the chooser to the top-level main window, not `this` child control.
+				chooser.ShowDialog(m_propertyTable.GetValue<Form>("window"));
 				if (chooser.DialogResult == DialogResult.OK)
 				{
 					if (chooser.ChosenObjects != null && chooser.ChosenObjects.Count() > 0)