Index: uspace/lib/gui/window.c
===================================================================
--- uspace/lib/gui/window.c	(revision c45d86965951801c4c148dc63314ade9ee2059d0)
+++ uspace/lib/gui/window.c	(revision 3e640e540295e77c5c2e26976915369b05c0a5a8)
@@ -509,5 +509,5 @@
 			dpos.x = drect.p0.x;
 		else if (placement_flags & WINDOW_PLACEMENT_CENTER_X)
-			dpos.x = (drect.p0.x + drect.p0.y - width) / 2;
+			dpos.x = (drect.p0.x + drect.p1.x - width) / 2;
 		else
 			dpos.x = drect.p1.x - width;