From 83cb10bcbc02967e4428d3e53b9c26ad1276d7b0 Mon Sep 17 00:00:00 2001
From: Adrien Destugues <pulkomandy@pulkomandy.tk>
Date: Tue, 1 Mar 2022 18:53:21 +0100
Subject: [PATCH] stack&tile: don't allow stacking a window onto itself

Change-Id: Iefd4a49b5b4caf2c3cd478a77fe4673dcac40427
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5056
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
---
 src/servers/app/stackandtile/Stacking.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/servers/app/stackandtile/Stacking.cpp b/src/servers/app/stackandtile/Stacking.cpp
index 94bcba8fb2..1ba120df62 100644
--- a/src/servers/app/stackandtile/Stacking.cpp
+++ b/src/servers/app/stackandtile/Stacking.cpp
@@ -69,6 +69,14 @@ StackingEventHandler::HandleMessage(SATWindow* sender,
 			SATWindow* candidate = stackAndTile->GetSATWindow(window);
 			if (!candidate)
 				return false;
+
+			// Is that window already part of the stack?
+			if (area->WindowList().HasItem(candidate)) {
+				reply.StartMessage(B_MISMATCHED_VALUES);
+				reply.Flush();
+				break;
+			}
+
 			if (!parent->StackWindow(candidate))
 				return false;