diff --git a/lcl/include/customform.inc b/lcl/include/customform.inc
index c893626617..a5f77c7d2c 100644
--- a/lcl/include/customform.inc
+++ b/lcl/include/customform.inc
@@ -116,8 +116,12 @@ var
       // for unknown reasons on some systems SM_*MAXIMIZED* system metrics
       // (tested xubuntu,64bits) return 0 or negative values, in this case
       // a maximized window is expected to have at least WorkArea width/height.
-      // In the event WorkArea is also 0 width/height, at least
-      // design sizes should be respected, see bug #21634
+      //
+      // Reproduced again under Debian Wheezy.
+      // mistery solved, it ocurrs under gtk2/64-bit, fixed at the place
+      // the checks doesn't hurt though
+      //
+      // see bug #21634
       if NewWidth<=0 then
         NewWidth := Screen.WorkAreaWidth;
       if NewHeight<=0 then
diff --git a/lcl/interfaces/gtk2/gtk2proc.inc b/lcl/interfaces/gtk2/gtk2proc.inc
index cb681d07b8..73fd257eb0 100644
--- a/lcl/interfaces/gtk2/gtk2proc.inc
+++ b/lcl/interfaces/gtk2/gtk2proc.inc
@@ -9352,7 +9352,8 @@ var
   Format: gint;
   nitems: gulong;
   bytes_after: gulong;
-  current_desktop: pguint;
+  current_desktop: pclong; // format=32 returns an array of "c" longs which in 64-bit app
+                           // will be 64-bit values that are padded in the upper 4 bytes
   res   : Integer;
 begin
   Result := -1;