diff --git a/lcl/interfaces/gtk2/gtk2wsforms.pp b/lcl/interfaces/gtk2/gtk2wsforms.pp
index 6e17fbe221..f768b57758 100644
--- a/lcl/interfaces/gtk2/gtk2wsforms.pp
+++ b/lcl/interfaces/gtk2/gtk2wsforms.pp
@@ -706,7 +706,7 @@ var
       (AForm.Parent = nil) and
       (AForm.FormStyle <> fsMDIChild) and
       (ModalWindows <> nil) and (ModalWindows.Count > 0) and
-      (AForm.BorderStyle in [bsDialog, bsSingle, bsSizeable]) and
+      (AForm.BorderStyle in [bsDialog, bsSingle, bsSizeable, bsSizeToolWin, bsToolWindow]) and
       (AForm.PopupParent = nil) and (AForm.PopupMode = pmNone) then
     begin
       AWindow := {%H-}PGtkWindow(AForm.Handle);