diff --git a/lcl/interfaces/gtk2/gtk2globals.pp b/lcl/interfaces/gtk2/gtk2globals.pp
index b81d641be5..b63ac85b7d 100644
--- a/lcl/interfaces/gtk2/gtk2globals.pp
+++ b/lcl/interfaces/gtk2/gtk2globals.pp
@@ -73,6 +73,19 @@ var
 
 var
   Styles : TStrings;
+
+const
+  //(bsNone, bsSingle, bsSizeable, bsDialog, bsToolWindow, bsSizeToolWin);
+  GtkWindowTypeHints: array[TFormBorderStyle] of TGdkWindowTypeHint = (
+  GDK_WINDOW_TYPE_HINT_NOTIFICATION,
+  GDK_WINDOW_TYPE_HINT_NORMAL,
+  GDK_WINDOW_TYPE_HINT_NORMAL,
+  GDK_WINDOW_TYPE_HINT_DIALOG,
+  GDK_WINDOW_TYPE_HINT_UTILITY,
+  GDK_WINDOW_TYPE_HINT_UTILITY
+  );
+
+var
   DefaultPangoLayout: PPangoLayout = nil;
 
 const
diff --git a/lcl/interfaces/gtk2/gtk2lclintf.inc b/lcl/interfaces/gtk2/gtk2lclintf.inc
index d1283a7b50..805cbae197 100644
--- a/lcl/interfaces/gtk2/gtk2lclintf.inc
+++ b/lcl/interfaces/gtk2/gtk2lclintf.inc
@@ -1276,12 +1276,13 @@ begin
     gtk_window_set_title(PGtkWindow(Dialog), PGChar(Title));
   end;
 
-  if (gtk_major_version = 2) and (gtk_minor_version <= 12) then
-  begin
-    ActiveWindow := GetActiveWindow;
-    if ActiveWindow <> 0 then
-      gtk_window_set_transient_for(PGtkWindow(Dialog), {%H-}PGtkWindow(ActiveWindow));
-  end;
+  ActiveWindow := GetActiveWindow;
+  if ActiveWindow <> 0 then
+    gtk_window_set_transient_for(PGtkWindow(Dialog), {%H-}PGtkWindow(ActiveWindow));
+  // the following line keeps the old behaviour making the dialog appear
+  // at screen center instead of at ActiveWindow center
+  gtk_window_set_position(PGtkWindow(Dialog), GTK_WIN_POS_CENTER);
+
   gtk_dialog_run(PGtkDialog(Dialog));
   gtk_widget_destroy(Dialog);
   Result := ADialogResult;
diff --git a/lcl/interfaces/gtk2/gtk2wsforms.pp b/lcl/interfaces/gtk2/gtk2wsforms.pp
index aa61c2e91f..16774fecf0 100644
--- a/lcl/interfaces/gtk2/gtk2wsforms.pp
+++ b/lcl/interfaces/gtk2/gtk2wsforms.pp
@@ -725,6 +725,8 @@ begin
     if AForm.HandleObjectShouldBeVisible and
       GTK_IS_WINDOW({%H-}PGtkWindow(AForm.Handle)) then
       begin
+        gtk_window_set_type_hint({%H-}PGtkWindow(AForm.Handle),
+           GtkWindowTypeHints[AForm.BorderStyle]);
         gtk_window_set_keep_above({%H-}PGtkWindow(AForm.Handle),
           GBoolean(AForm.FormStyle in fsAllStayOnTop))
       end
@@ -739,7 +741,6 @@ begin
   begin
     gtk_window_set_default_size(GtkWindow, Max(1,AForm.Width), Max(1,AForm.Height));
     gtk_widget_set_uposition(PGtkWidget(GtkWindow), AForm.Left, AForm.Top);
-    gtk_window_set_type_hint(GtkWindow, GDK_WINDOW_TYPE_HINT_DIALOG);
     GtkWindowShowModal(AForm, GtkWindow);
   end else
   begin