diff --git a/src/client/client.c b/src/client/client.c
index 0535c1cf..956d7f58 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -189,12 +189,14 @@ static void process_socket_message (MSG *msg)
         /* Since 5.2.0 */
         int slot = (int)msg->wParam;
         HWND hwnd = (HWND)msg->lParam;
+        unsigned dirty_age = (unsigned)msg->time;
         if (__mg_client_check_znode_hwnd(slot, hwnd, __mg_client_id)) {
             GAL_Surface *ssurf = ((PMAINWIN)hwnd)->surf;
             assert(ssurf->shared_header);
             __mg_lock_file_for_write(ssurf->fd);
-            ssurf->dirty_info->nr_dirty_rcs = 0;
-            ssurf->dirty_info->dirty_age++;
+            if (ssurf->dirty_info->dirty_age == dirty_age) {
+                ssurf->dirty_info->nr_dirty_rcs = 0;
+            }
             __mg_unlock_file_for_write(ssurf->fd);
         }
     }
diff --git a/src/kernel/compsor-fallback.c b/src/kernel/compsor-fallback.c
index 7c35ac3f..7d71c9f2 100644
--- a/src/kernel/compsor-fallback.c
+++ b/src/kernel/compsor-fallback.c
@@ -679,6 +679,19 @@ static BOOL merge_dirty_ppp (CompositorCtxt* ctxt, MG_Layer* layer, int zidx)
     return rc;
 }
 
+#if 0
+static void dump_dirty_region(CompositorCtxt* ctxt, const char *prefix, int zidx)
+{
+    CLIPRGN* rgn = &ctxt->dirty_rgn;
+    _WRN_PRINTF("%s (%d): dirty region on screen: (%d, %d) %d x %d; "
+            "highest dirty win: %d; lowest dirty win: %d\n",
+            prefix, zidx,
+            rgn->rcBound.left, rgn->rcBound.top,
+            RECTW (rgn->rcBound), RECTH (rgn->rcBound),
+            ctxt->highest_dirty_win, ctxt->lowest_dirty_win);
+}
+#endif
+
 static BOOL merge_dirty_win (CompositorCtxt* ctxt, MG_Layer* layer, int zidx)
 {
     BOOL rc = FALSE;
@@ -722,9 +735,13 @@ static BOOL merge_dirty_wpp (CompositorCtxt* ctxt, MG_Layer* layer)
 static BOOL refresh_dirty_region (CompositorCtxt* ctxt, MG_Layer* layer)
 {
     /* the fallback compositor only manages znodes on the topmost layer. */
-    if (layer != mgTopmostLayer || IsEmptyClipRgn (&ctxt->dirty_rgn))
+    if (layer != mgTopmostLayer)
         return FALSE;
 
+    if (IsEmptyClipRgn (&ctxt->dirty_rgn)) {
+        return FALSE;
+    }
+
     if (ctxt->highest_dirty_ppp >= 0) {
         composite_ppp_znodes (ctxt);
     }
diff --git a/src/kernel/compsor-manager.c b/src/kernel/compsor-manager.c
index fea53aaf..044775d0 100644
--- a/src/kernel/compsor-manager.c
+++ b/src/kernel/compsor-manager.c
@@ -68,6 +68,7 @@
 #include "constants.h"
 #include "zorder.h"
 #include "dc.h"
+#include "server.h"
 
 #define MAX_NR_COMPOSITORS      8
 #define LEN_COMPOSITOR_NAME     15
@@ -138,7 +139,6 @@ static void lock_znode_surface (PDC pdc, ZORDERNODE* node)
         node->dirty_age = pdc->surface->dirty_info->dirty_age;
         node->nr_dirty_rcs = pdc->surface->dirty_info->nr_dirty_rcs;
         node->dirty_rcs = pdc->surface->dirty_info->dirty_rcs;
-
     }
 
     node->lock_count++;
@@ -174,8 +174,9 @@ static void reset_znode_surface_dirty (PDC pdc, ZORDERNODE* node, int slot)
         pdc->surface->dirty_info->nr_dirty_rcs = 0;
     }
     else if (node->hwnd) {
-        MSG msg = { HWND_NULL, MSG_WINCOMPOSITED, slot, (LPARAM)node->hwnd };
-        __mg_send2client(&msg, node);
+        MSG msg = { HWND_NULL, MSG_WINCOMPOSITED,
+            slot, (LPARAM)node->hwnd, (DWORD)node->changes };
+        __mg_send2client(&msg, mgClients + node->cli);
     }
 }
 
diff --git a/src/kernel/desktop.c b/src/kernel/desktop.c
index 5ab17cb0..c6e63fd7 100644
--- a/src/kernel/desktop.c
+++ b/src/kernel/desktop.c
@@ -1654,6 +1654,8 @@ static int srvStartTrackPopupMenu (int cli, const RECT* rc, HWND ptmi,
     menu_nodes [zi->nr_popupmenus].ct = CT_OPAQUE;
     menu_nodes [zi->nr_popupmenus].ct_arg = 0;
     menu_nodes [zi->nr_popupmenus].mem_dc = memdc;
+    menu_nodes [zi->nr_popupmenus].dirty_age = 0;
+    menu_nodes [zi->nr_popupmenus].nr_dirty_rcs = 0;
     menu_nodes [zi->nr_popupmenus].dirty_rcs = NULL;
 #endif
     menu_nodes [zi->nr_popupmenus].priv_data = NULL;
@@ -2359,6 +2361,8 @@ static int AllocZOrderNodeEx (ZORDERINFO* zi, int cli, HWND hwnd, HWND main_win,
     nodes [free_slot].ct = validate_compositing_type (flags, ct);
     nodes [free_slot].ct_arg = ct_arg;
     nodes [free_slot].mem_dc = mem_dc;
+    nodes [free_slot].dirty_age = 0;
+    nodes [free_slot].nr_dirty_rcs = 0;
     nodes [free_slot].dirty_rcs = NULL;
 #else
     nodes [free_slot].age = 1;
diff --git a/src/misc/lock_file.c b/src/misc/lock_file.c
index 5f73fc02..878e8b67 100644
--- a/src/misc/lock_file.c
+++ b/src/misc/lock_file.c
@@ -63,22 +63,50 @@
 
 void __mg_lock_file_for_read(int fd)
 {
-    while (flock(fd, LOCK_SH) == -1 && errno == EINTR);
+    struct flock lock;
+
+    lock.l_type = F_RDLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+
+    while (fcntl(fd, F_SETLKW, &lock) == -1 && errno == EINTR);
 }
 
 void __mg_unlock_file_for_read(int fd)
 {
-    flock(fd, LOCK_UN);
+    struct flock lock;
+
+    lock.l_type = F_UNLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+
+    fcntl(fd, F_SETLK, &lock);
 }
 
 void __mg_lock_file_for_write(int fd)
 {
-    while (flock(fd, LOCK_EX) == -1 && errno == EINTR);
+    struct flock lock;
+
+    lock.l_type = F_WRLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+
+    while (fcntl(fd, F_SETLKW, &lock) == -1 && errno == EINTR);
 }
 
 void __mg_unlock_file_for_write(int fd)
 {
-    flock(fd, LOCK_UN);
+    struct flock lock;
+
+    lock.l_type = F_UNLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+
+    fcntl(fd, F_SETLK, &lock);
 }
 
 #endif /* __NOUNIX__ */
diff --git a/src/newgdi/region.c b/src/newgdi/region.c
index 8576665d..0c8a63d7 100644
--- a/src/newgdi/region.c
+++ b/src/newgdi/region.c
@@ -269,7 +269,7 @@ void GUIAPI GetClipRgnBoundRect (PCLIPRGN pRgn, PRECT pRect)
 
 BOOL GUIAPI IsEmptyClipRgn (const CLIPRGN* pRgn)
 {
-     if (pRgn->head == NULL)
+     if (pRgn->head == NULL || IsRectEmpty (&pRgn->rcBound))
          return TRUE;
 
      return FALSE;