diff --git a/ddraw.rc b/ddraw.rc
index 8c28da4..f85821a 100644
--- a/ddraw.rc
+++ b/ddraw.rc
@@ -1,6 +1,6 @@
 1 VERSIONINFO
-FILEVERSION 1,1,5,5
-PRODUCTVERSION 1,1,5,5
+FILEVERSION 1,1,5,6
+PRODUCTVERSION 1,1,5,6
 {
     BLOCK "StringFileInfo"
     {
@@ -8,13 +8,13 @@ PRODUCTVERSION 1,1,5,5
         {
             VALUE "CompanyName", "cncnet.org"
             VALUE "FileDescription", "DirectDraw replacement for C&C95 and Red Alert"
-            VALUE "FileVersion", "1.1.5.5"
+            VALUE "FileVersion", "1.1.5.6"
             VALUE "InternalName", "ddraw"
             VALUE "LegalCopyright", "Copyright (c) 2010-2018"
             VALUE "LegalTrademarks", ""
             VALUE "OriginalFileName", "ddraw.dll"
             VALUE "ProductName", "DirectDraw replacement for C&C95 and Red Alert"
-            VALUE "ProductVersion", "1.1.5.5"
+            VALUE "ProductVersion", "1.1.5.6"
             VALUE "Comments", "https://cncnet.org"
         }
     }
diff --git a/inc/main.h b/inc/main.h
index 4fe056e..8a200f2 100644
--- a/inc/main.h
+++ b/inc/main.h
@@ -67,6 +67,7 @@ typedef struct IDirectDrawImpl
         HANDLE ev;
         HANDLE sem;
         DEVMODE mode;
+        struct { int width; int height; int x; int y; } viewport;
 
     } render;
 
diff --git a/src/main.c b/src/main.c
index 9f7a403..fbd6ad7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -362,6 +362,47 @@ HRESULT __stdcall ddraw_SetDisplayMode(IDirectDrawImpl *This, DWORD width, DWORD
         }
     }
     
+    ddraw->render.viewport.width = ddraw->render.width;
+    ddraw->render.viewport.height = ddraw->render.height;
+    ddraw->render.viewport.x = 0;
+    ddraw->render.viewport.y = 0;
+    
+    if (ddraw->boxing)
+    {
+        ddraw->render.viewport.width = ddraw->width;
+        ddraw->render.viewport.height = ddraw->height;
+
+        int i;
+        for (i = 20; i-- > 1;)
+        {
+            if (ddraw->width * i <= ddraw->render.width && ddraw->height * i <= ddraw->render.height)
+            {
+                ddraw->render.viewport.width *= i;
+                ddraw->render.viewport.height *= i;
+                break;
+            }
+        }
+
+        ddraw->render.viewport.y = ddraw->render.height / 2 - ddraw->render.viewport.height / 2;
+        ddraw->render.viewport.x = ddraw->render.width / 2 - ddraw->render.viewport.width / 2;
+    }
+    else if (ddraw->maintas)
+    {
+        ddraw->render.viewport.width = ddraw->render.width;
+        ddraw->render.viewport.height = ((float)ddraw->height / ddraw->width) * ddraw->render.viewport.width;
+        
+        if (ddraw->render.viewport.height > ddraw->render.height)
+        {
+            ddraw->render.viewport.width = 
+                ((float)ddraw->render.viewport.width / ddraw->render.viewport.height) * ddraw->render.height;
+                
+            ddraw->render.viewport.height = ddraw->render.height;
+        }
+         
+        ddraw->render.viewport.y = ddraw->render.height / 2 - ddraw->render.viewport.height / 2;
+        ddraw->render.viewport.x = ddraw->render.width / 2 - ddraw->render.viewport.width / 2;
+    }
+    
     if(This->windowed)
     {
         if(!This->windowed_init)
@@ -596,8 +637,26 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
         case WM_MBUTTONUP:
             if (!ddraw->devmode && !ddraw->locked)
             {
-                ddraw->cursor.x = LOWORD(lParam) * ((float)ddraw->width / ddraw->render.width);
-                ddraw->cursor.y = HIWORD(lParam) * ((float)ddraw->height / ddraw->render.height);
+                int x = LOWORD(lParam);
+                int y = HIWORD(lParam);
+                
+                if (x > ddraw->render.viewport.x + ddraw->render.viewport.width || 
+                    x < ddraw->render.viewport.x || 
+                    y > ddraw->render.viewport.y + ddraw->render.viewport.height ||
+                    y < ddraw->render.viewport.y)
+                {
+                    ddraw->cursor.x = ddraw->width / 2;
+                    ddraw->cursor.y = ddraw->height / 2;
+                }    
+                else
+                {
+                    ddraw->cursor.x = 
+                        (x - ddraw->render.viewport.x) * ((float)ddraw->width / ddraw->render.viewport.width);
+                        
+                    ddraw->cursor.y = 
+                        (y - ddraw->render.viewport.y) * ((float)ddraw->height / ddraw->render.viewport.height);
+                }
+
                 mouse_lock();
                 return 0;
             }
diff --git a/src/mouse.c b/src/mouse.c
index 5e62133..87fabcc 100644
--- a/src/mouse.c
+++ b/src/mouse.c
@@ -44,8 +44,8 @@ BOOL WINAPI fake_GetCursorPos(LPPOINT lpPoint)
     {
         if(ddraw->adjmouse)
         {
-            ddraw->cursor.x = pt.x * ((float)ddraw->width / ddraw->render.width);
-            ddraw->cursor.y = pt.y * ((float)ddraw->height / ddraw->render.height);
+            ddraw->cursor.x = pt.x * ((float)ddraw->width / ddraw->render.viewport.width);
+            ddraw->cursor.y = pt.y * ((float)ddraw->height / ddraw->render.viewport.height);
         }
         else
         {
@@ -53,7 +53,7 @@ BOOL WINAPI fake_GetCursorPos(LPPOINT lpPoint)
             ddraw->cursor.y = pt.y;
         }
     }
-        
+
     if (lpPoint)
     {
         lpPoint->x = (int)ddraw->cursor.x;
@@ -178,11 +178,15 @@ void mouse_lock()
         // Get the window client area.
         GetClientRect(ddraw->hWnd, &rc);
         
-        if(!ddraw->adjmouse)
+        if(ddraw->adjmouse)
         {
-            // stretching fix
-            rc.right -= (ddraw->render.width - ddraw->width);
-            rc.bottom -= (ddraw->render.height - ddraw->height);
+            rc.right = ddraw->render.viewport.width;
+            rc.bottom = ddraw->render.viewport.height;
+        }
+        else
+        {
+            rc.right = ddraw->width;
+            rc.bottom = ddraw->height;
         }
 
         // Convert the client area to screen coordinates.
@@ -193,13 +197,13 @@ void mouse_lock()
         
         SetRect(&rc, pt.x, pt.y, pt2.x, pt2.y);
         
-        rc.bottom -= (yAdjust * 2) * ((float)ddraw->render.height / ddraw->height);
+        rc.bottom -= (yAdjust * 2) * ((float)ddraw->render.viewport.height / ddraw->height);
 
         if(ddraw->adjmouse)
         {
             SetCursorPos(
-                rc.left + (ddraw->cursor.x * ((float)ddraw->render.width / ddraw->width)), 
-                rc.top + ((ddraw->cursor.y - yAdjust) * ((float)ddraw->render.height / ddraw->height)));
+                rc.left + (ddraw->cursor.x * ((float)ddraw->render.viewport.width / ddraw->width)), 
+                rc.top + ((ddraw->cursor.y - yAdjust) * ((float)ddraw->render.viewport.height / ddraw->height)));
         }
         else
         {
@@ -250,8 +254,10 @@ void mouse_unlock()
         ReleaseCapture();
         
         SetCursorPos(
-            rc.left + (ddraw->cursor.x * ((float)ddraw->render.width / ddraw->width)), 
-            rc.top + ((ddraw->cursor.y + yAdjust) * ((float)ddraw->render.height / ddraw->height)));
+            rc.left + ddraw->render.viewport.x + 
+                (ddraw->cursor.x * ((float)ddraw->render.viewport.width / ddraw->width)), 
+            rc.top + ddraw->render.viewport.y + 
+                ((ddraw->cursor.y + yAdjust) * ((float)ddraw->render.viewport.height / ddraw->height)));
 
     }
 }
diff --git a/src/render.c b/src/render.c
index 7a55c8f..5e193f7 100644
--- a/src/render.c
+++ b/src/render.c
@@ -118,46 +118,9 @@ DWORD WINAPI render_main(void)
     glBindTexture(GL_TEXTURE_2D, textureId);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, tex_width, tex_height, 0, PIXEL_FORMAT, GL_UNSIGNED_BYTE, tex);
 
-    DWORD dst_top = 0;
-    DWORD dst_left = 0;
-    DWORD dst_width = ddraw->render.width;
-    DWORD dst_height = ddraw->render.height;
-    
-    if (ddraw->boxing)
-    {
-        dst_width = ddraw->width;
-        dst_height = ddraw->height;
-
-        int i;
-        for (i = 20; i-- > 1;)
-        {
-            if (ddraw->width * i <= ddraw->render.width && ddraw->height * i <= ddraw->render.height)
-            {
-                dst_width *= i;
-                dst_height *= i;
-                break;
-            }
-        }
-
-        dst_top = ddraw->render.height / 2 - dst_height / 2;
-        dst_left = ddraw->render.width / 2 - dst_width / 2;
-    }
-    else if (ddraw->maintas)
-    {
-        dst_width = ddraw->render.width;
-        dst_height = ((float)ddraw->height / ddraw->width) * dst_width;
-        
-        if (dst_height > ddraw->render.height)
-        {
-            dst_width = ((float)dst_width / dst_height) * ddraw->render.height;
-            dst_height = ddraw->render.height;
-        }
-         
-        dst_top = ddraw->render.height / 2 - dst_height / 2;
-        dst_left = ddraw->render.width / 2 - dst_width / 2;
-    }
-
-    glViewport(dst_left, dst_top, dst_width, dst_height);
+    glViewport(
+        ddraw->render.viewport.x, ddraw->render.viewport.y, 
+        ddraw->render.viewport.width, ddraw->render.viewport.height);
     
     if(ddraw->render.filter)
     {
diff --git a/src/render_soft.c b/src/render_soft.c
index 6e4c014..553e55b 100644
--- a/src/render_soft.c
+++ b/src/render_soft.c
@@ -60,49 +60,10 @@ DWORD WINAPI render_soft_main(void)
     bmi->bmiHeader.biBitCount = ddraw->bpp;
     bmi->bmiHeader.biCompression = BI_RGB;
 
-    DWORD dst_top = 0;
-    DWORD dst_left = 0;
-    DWORD dst_width = ddraw->render.width;
-    DWORD dst_height = ddraw->render.height;
-
     DWORD tick_start = 0;
     DWORD tick_end = 0;
     DWORD frame_len = 0;
 
-    if (ddraw->boxing)
-    {
-        dst_width = ddraw->width;
-        dst_height = ddraw->height;
-
-        int i;
-        for (i = 20; i-- > 1;)
-        {
-            if (ddraw->width * i <= ddraw->render.width && ddraw->height * i <= ddraw->render.height)
-            {
-                dst_width *= i;
-                dst_height *= i;
-                break;
-            }
-        }
-
-        dst_top = ddraw->render.height / 2 - dst_height / 2;
-        dst_left = ddraw->render.width / 2 - dst_width / 2;
-    }
-    else if (ddraw->maintas)
-    {
-        dst_width = ddraw->render.width;
-        dst_height = ((float)ddraw->height / ddraw->width) * dst_width;
-        
-        if (dst_height > ddraw->render.height)
-        {
-            dst_width = ((float)dst_width / dst_height) * ddraw->render.height;
-            dst_height = ddraw->render.height;
-        }
-         
-        dst_top = ddraw->render.height / 2 - dst_height / 2;
-        dst_left = ddraw->render.width / 2 - dst_width / 2;
-    }
-
     if(ddraw->render.maxfps < 0)
     {
         ddraw->render.maxfps = ddraw->mode.dmDisplayFrequency;
@@ -144,7 +105,7 @@ DWORD WINAPI render_soft_main(void)
 
             if ((ddraw->render.width != ddraw->width || ddraw->render.height != ddraw->height) && !(ddraw->vhack && detect_cutscene()) )
             {
-                StretchDIBits(ddraw->render.hDC, dst_left, dst_top, dst_width, dst_height, 0, 0, ddraw->width, ddraw->height, ddraw->primary->surface, bmi, DIB_RGB_COLORS, SRCCOPY);
+                StretchDIBits(ddraw->render.hDC, ddraw->render.viewport.x, ddraw->render.viewport.y, ddraw->render.viewport.width, ddraw->render.viewport.height, 0, 0, ddraw->width, ddraw->height, ddraw->primary->surface, bmi, DIB_RGB_COLORS, SRCCOPY);
             }
             else if (!(ddraw->vhack && detect_cutscene()))
             {