diff --git a/kernel/trunk/gui/mouse.inc b/kernel/trunk/gui/mouse.inc
index 8dc359fe26..68590dd102 100644
--- a/kernel/trunk/gui/mouse.inc
+++ b/kernel/trunk/gui/mouse.inc
@@ -371,6 +371,7 @@ mouse._.move_handler:
         cmp     eax, [_display.width]
         jl      @f
         sub     eax, [_display.width]
+        inc     eax
         sub     [mouse.active_sys_window.new_box.left], eax
     @@:
         mov     eax, [mouse.active_sys_window.new_box.top]
@@ -383,6 +384,7 @@ mouse._.move_handler:
         cmp     eax, [_display.height]
         jl      .call_window_handler
         sub     eax, [_display.height]
+        inc     eax
         sub     [mouse.active_sys_window.new_box.top], eax
         jmp     .call_window_handler
 
diff --git a/kernel/trunk/gui/window.inc b/kernel/trunk/gui/window.inc
index 5ee563b0dd..6b1e7e19b0 100644
--- a/kernel/trunk/gui/window.inc
+++ b/kernel/trunk/gui/window.inc
@@ -1686,7 +1686,8 @@ align 4
 align 4
 .fix_width_high:
         mov     ecx, esi
-        mov     [edi + WDATA.box.width], esi
+        dec     ecx
+        mov     [edi + WDATA.box.width], ecx
         jmp     .check_left
 ;--------------------------------------
 align 4
@@ -1699,13 +1700,15 @@ align 4
 .fix_left_high:
         mov     eax, esi
         sub     eax, ecx
+        dec     eax
         mov     [edi + WDATA.box.left], eax
         jmp     .check_height
 ;--------------------------------------
 align 4
 .fix_height_high:
         mov     edx, esi
-        mov     [edi + WDATA.box.height], esi
+        dec     edx
+        mov     [edi + WDATA.box.height], edx
         jmp     .check_top
 ;--------------------------------------
 align 4
@@ -1718,6 +1721,7 @@ align 4
 .fix_top_high:
         mov     ebx, esi
         sub     ebx, edx
+        dec     ebx
         mov     [edi + WDATA.box.top], ebx
         jmp     .exit
 ;------------------------------------------------------------------------------