--- xorg-server-1.20.1.orig/hw/xwin/winwindow.c	2018-08-07 18:31:04.000000000 +0200

+++ xorg-server-1.20.1/hw/xwin/winwindow.c	2018-08-22 19:39:37.078925268 +0200

@@ -269,14 +269,14 @@

             if (pWinPriv->hRgn) {

                 if (CombineRgn(hRgnWin, hRgnWin, pWinPriv->hRgn, RGN_AND)

-                    == ERROR) {

+                    == 0) {

                     ErrorF("winAddRgn - CombineRgn () failed\n");

                 }

             }

             OffsetRgn(hRgnWin, iX, iY);

-            if (CombineRgn(hRgn, hRgn, hRgnWin, RGN_OR) == ERROR) {

+            if (CombineRgn(hRgn, hRgn, hRgnWin, RGN_OR) == 0) {

                 ErrorF("winAddRgn - CombineRgn () failed\n");

             }

@@ -363,7 +363,7 @@

             }

             /* Merge the Windows region with the accumulated region */

-            if (CombineRgn(hRgn, hRgn, hRgnRect, RGN_OR) == ERROR) {

+            if (CombineRgn(hRgn, hRgn, hRgnRect, RGN_OR) == 0) {

                 ErrorF("winReshapeRootless - CombineRgn() failed\n");

             }