diff --git a/mozilla/extensions/help/resources/content/help.xul b/mozilla/extensions/help/resources/content/help.xul
index c58c5b72bc0..d7a52a5d61a 100644
--- a/mozilla/extensions/help/resources/content/help.xul
+++ b/mozilla/extensions/help/resources/content/help.xul
@@ -187,8 +187,6 @@
       <splitter id="helpsidebar-splitter"
                 collapse="before"
                 persist="state hidden"
-                autostretch="never"
-                orient="vertical"
                 state="open">
         <grippy/>
       </splitter>
diff --git a/mozilla/extensions/inspector/resources/content/inspectorOverlay.xul b/mozilla/extensions/inspector/resources/content/inspectorOverlay.xul
index b516c1e6755..cb5ee2a46cf 100644
--- a/mozilla/extensions/inspector/resources/content/inspectorOverlay.xul
+++ b/mozilla/extensions/inspector/resources/content/inspectorOverlay.xul
@@ -33,7 +33,7 @@
       <domi:panel id="bxDocPanel" title="&bxDocPanel.title;" 
                   flex="1" persist="width"/>
 
-      <splitter id="splPanels" orient="vertical"/>
+      <splitter id="splPanels"/>
       
       <domi:panel id="bxObjectPanel" title="&bxObjectPanel.title;" linkedpanel="bxDocPanel"
                   flex="1" persist="width"/>
diff --git a/mozilla/extensions/inspector/resources/content/viewers/styleRules/styleRules.xul b/mozilla/extensions/inspector/resources/content/viewers/styleRules/styleRules.xul
index 17abb79462b..6137f5add1f 100644
--- a/mozilla/extensions/inspector/resources/content/viewers/styleRules/styleRules.xul
+++ b/mozilla/extensions/inspector/resources/content/viewers/styleRules/styleRules.xul
@@ -59,7 +59,7 @@
     <outlinerbody id="olbStyleRules" flex="1"/>
   </outliner>
   
-  <splitter orient="horizontal" collapse="after">
+  <splitter collapse="after">
     <grippy/>
   </splitter>
 
diff --git a/mozilla/extensions/irc/xul/content/chatzilla.xul b/mozilla/extensions/irc/xul/content/chatzilla.xul
index c30499baf17..3a8f92b3f1c 100644
--- a/mozilla/extensions/irc/xul/content/chatzilla.xul
+++ b/mozilla/extensions/irc/xul/content/chatzilla.xul
@@ -357,8 +357,7 @@
   
       </vbox> <!-- user-list-box -->
 
-      <splitter id="main-splitter" orient="vertical" collapse="before"
-        persist="collapsed left">
+      <splitter id="main-splitter" collapse="before" persist="collapsed left">
         <grippy/>
       </splitter>
 
@@ -387,8 +386,7 @@
 
   </vbox> <!-- upper-box -->
 
-  <splitter id="input-splitter" orient="vertical" collapse="after"
-    collapsed="true"/>
+  <splitter id="input-splitter" collapse="after" collapsed="true"/>
 
   <vbox id="input-widgets">
     <textbox id="multiline-input" multiline="true" flex="1" height="100px"
diff --git a/mozilla/layout/xul/base/src/nsSplitterFrame.cpp b/mozilla/layout/xul/base/src/nsSplitterFrame.cpp
index 58d626d4cc8..e7d5e55cacf 100644
--- a/mozilla/layout/xul/base/src/nsSplitterFrame.cpp
+++ b/mozilla/layout/xul/base/src/nsSplitterFrame.cpp
@@ -339,6 +339,25 @@ nsSplitterFrame::Init(nsIPresContext*  aPresContext,
   else */
      realTimeDrag = 1;
 
+  // determine orientation of parent, and if vertical, set orient to vertical
+  // on splitter content, then re-resolve style
+  nsIBox* boxParent;
+  if (aParent)
+    CallQueryInterface(aParent, &boxParent);
+  if (boxParent) {
+    PRBool isHorizontal;
+    boxParent->GetOrientation(isHorizontal);
+    if (!isHorizontal) {
+      nsAutoString str;
+      aContent->GetAttr(kNameSpaceID_None, nsXULAtoms::orient, str);
+      if (str.IsEmpty()) {
+        aContent->SetAttr(kNameSpaceID_None, nsXULAtoms::orient,
+                          NS_LITERAL_STRING("vertical"), PR_FALSE);
+        aPresContext->ResolveStyleContextFor(aContent, aContext->GetParent(), PR_FALSE, &aContext);
+      }
+    }
+  }
+
   nsresult  rv = nsBoxFrame::Init(aPresContext, aContent, aParent, aContext, aPrevInFlow);
 
   // XXX Hack because we need the pres context in some of the event handling functions...
diff --git a/mozilla/themes/classic/global/mac/splitter.css b/mozilla/themes/classic/global/mac/splitter.css
index fe69ddac5ee..00abf2d6de0 100644
--- a/mozilla/themes/classic/global/mac/splitter.css
+++ b/mozilla/themes/classic/global/mac/splitter.css
@@ -48,7 +48,7 @@ splitter:hover:active
   }
 
 /* vertical splitters */
-  window > splitter, box, hbox > splitter 
+  splitter
     {
     	width               : 6px;
     }
@@ -56,10 +56,7 @@ splitter:hover:active
 /* horizontal splitters */  
   /* XXX 'align' support removed to force people to migrate 
          to 'orient' */
-  rows > splitter,
-  window[orient="vertical"] > splitter,
-  box[orient="vertical"] > splitter,
-  vbox > splitter
+  splitter[orient="vertical"]
     {
       cursor              : n-resize;
       border-right		  : 0px;
@@ -70,19 +67,13 @@ splitter:hover:active
 /**** NOTE *****/
 /* The images below are correct, even though their names are switched. */
 
-  window[orient="vertical"] > splitter > grippy,
-  window[orient="vertical"] > splitter > grippy[collapse="before"],
-  vbox > splitter > grippy,
-  vbox > splitter > grippy[collapse="before"],
-  box[orient="vertical"] > splitter > grippy,
-  box[orient="vertical"] > splitter > grippy[collapse="before"]
+  splitter[orient="vertical"] > grippy,
+  splitter[orient="vertical"] > grippy[collapse="before"]
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-after.gif");
     }
     
-  window[orient="vertical"] > splitter[state="collapsed"] > grippy,
-  vbox > splitter[state="collapsed"] > grippy,
-  box[orient="vertical"] > splitter[state="collapsed"] > grippy
+  splitter[state="collapsed"][orient="vertical"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-before.gif");
     }
diff --git a/mozilla/themes/classic/global/win/splitter.css b/mozilla/themes/classic/global/win/splitter.css
index 27e184f2c05..7e50cd00228 100644
--- a/mozilla/themes/classic/global/win/splitter.css
+++ b/mozilla/themes/classic/global/win/splitter.css
@@ -55,9 +55,7 @@
       cursor              : n-resize;
     }
     
-  window[orient="vertical"] > splitter,
-  box[orient="vertical"] > splitter,
-  vbox > splitter
+  splitter[orient="vertical"]
     {
       cursor              : n-resize;
       border-top          : 1px solid ThreeDHighlight;
@@ -65,50 +63,37 @@
     
 /* Grippy alignment */
 
-/* Vertical splitter (between two boxes, horizontally stacked), collapse to left */
-  window > splitter > grippy,
-  box > splitter > grippy,
-  hbox > splitter > grippy
+  splitter > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-horizontal-before.gif");
       border-left         : none;
       border-right        : none;
     }  
     
-  window > splitter > grippy > .grippy-box,
-  box > splitter > grippy > .grippy-box,
-  hbox > splitter > grippy > .grippy-box 
+  splitter > grippy > .grippy-box
     {
       border-left         : none;
       border-right        : none;
     }  
 
-  window > splitter[state="collapsed"] > grippy,
-  box > splitter[state="collapsed"] > grippy,
-  hbox > splitter[state="collapsed"] > grippy
+  splitter[state="collapsed"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-horizontal-after.gif");
     }
 
 /* Vertical splitter (between two boxes, horizontally stacked), collapse to right */
-  window > splitter[collapse="after"] > grippy,
-  box > splitter[collapse="after"] > grippy,
-  hbox > splitter[collapse="after"] > grippy
+  splitter[collapse="after"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-horizontal-after.gif");
     }  
     
-  window > splitter[collapse="after"][state="collapsed"] > grippy,
-  box > splitter[collapse="after"][state="collapsed"] > grippy,
-  hbox > splitter[collapse="after"][state="collapsed"]> grippy
+  splitter[collapse="after"][state="collapsed"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-horizontal-before.gif");
     }
 
 /* Horizontal splitter (between two boxes, vertically stacked), collapse to left */
-  window[orient="vertical"] > splitter > grippy,
-  box[orient="vertical"] > splitter > grippy,
-  vbox > splitter > grippy
+  splitter[orient="vertical"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-before.gif");
       border-left         : 1px solid ThreeDShadow;
@@ -117,9 +102,7 @@
       border-bottom       : none;
     }  
     
-  window[orient="vertical"] > splitter > grippy > .grippy-box,
-  box[orient="vertical"] > splitter > grippy > .grippy-box,
-  vbox > splitter > grippy > .grippy-box
+  splitter[orient="vertical"] > grippy > .grippy-box
     {
       border-left         : 1px solid ThreeDHighlight;
       border-right        : 1px solid ThreeDShadow;
@@ -127,24 +110,18 @@
       border-bottom       : none;
     }  
 
-  window[orient="vertical"] > splitter[state="collapsed"] > grippy,
-  box[orient="vertical"] > splitter[state="collapsed"] > grippy,
-  vbox > splitter[state="collapsed"] > grippy
+  splitter[state="collapsed"][orient="vertical"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-after.gif");
     }
     
 /* Horizontal splitter (between two boxes, vertically stacked), collapse to right */
-  window[orient="vertical"] > splitter[collapse="after"] > grippy,
-  box[orient="vertical"] > splitter[collapse="after"] > grippy,
-  vbox > splitter[collapse="after"] > grippy
+  splitter[collapse="after"][orient="vertical"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-after.gif");
     }  
     
-  window[orient="vertical"] > splitter[collapse="after"][state="collapsed"] > grippy,
-  box[orient="vertical"] > splitter[collapse="after"][state="collapsed"] > grippy,
-  vbox > splitter[collapse="after"][state="collapsed"] > grippy
+  splitter[collapse="after"][state="collapsed"][orient="vertical"] > grippy
     {
       list-style-image    : url("chrome://global/skin/grippy-vertical-before.gif");
     }
diff --git a/mozilla/themes/modern/global/splitter.css b/mozilla/themes/modern/global/splitter.css
index 183835581f0..c7a74ebae39 100644
--- a/mozilla/themes/modern/global/splitter.css
+++ b/mozilla/themes/modern/global/splitter.css
@@ -47,10 +47,7 @@ splitter {
 
 /* ::::: splitter (horizontal) ::::: */
 
-rows > splitter,
-window[orient="vertical"] > splitter,
-vbox > splitter,
-box[orient="vertical"] > splitter {
+splitter[orient="vertical"] {
   cursor: n-resize;
   border-top: 1px solid #000000;
   border-right: none;
@@ -59,10 +56,7 @@ box[orient="vertical"] > splitter {
   min-width: 1px;
 }
 
-rows > splitter > .splitter-internal-box,
-window[orient="vertical"] > splitter > .splitter-internal-box,
-vbox > splitter > .splitter-internal-box,
-box[orient="vertical"] > splitter > .splitter-internal-box {
+splitter[orient="vertical"] > .splitter-internal-box {
   min-height: 5px;
 }
   
@@ -79,9 +73,7 @@ grippy {
   background-position: 50% 50%;
 }
 
-window[orient="vertical"] > splitter > grippy,
-vbox > splitter > grippy,
-box[orient="vertical"] > splitter > grippy {
+splitter[orient="vertical"] > grippy {
   width: 64px;
   height: 5px;
 }
@@ -98,15 +90,11 @@ splitter[collapse="after"] > grippy {
 }
 
 /* horizontal grippies */
-window[orient="vertical"] > splitter[collapse="before"] > grippy,
-vbox > splitter[collapse="before"] > grippy,
-box[orient="vertical"] > splitter[collapse="before"] > grippy {
+splitter[collapse="before"][orient="vertical"] > grippy {
   background-image: url("chrome://global/skin/splitter/grip-hrz-before.gif");
 }  
 
-window[orient="vertical"] > splitter[collapse="after"] > grippy,
-vbox > splitter[collapse="after"] > grippy,
-box[orient="vertical"] > splitter[collapse="after"] > grippy {
+splitter[collapse="after"][orient="vertical"] > grippy {
   background-image: url("chrome://global/skin/splitter/grip-hrz-after.gif");
 }  
   
@@ -122,15 +110,11 @@ splitter[collapse="after"] > grippy:hover:active {
 }
 
 /* horizontal grippies */
-window[orient="vertical"] > splitter[collapse="before"] > grippy:hover:active,
-vbox > splitter[collapse="before"] > grippy:hover:active,
-box[orient="vertical"] > splitter[collapse="before"] > grippy:hover:active {
+splitter[collapse="before"][orient="vertical"] > grippy:hover:active {
   background-image: url("chrome://global/skin/splitter/grip-hrz-act.gif");
 }  
 
-window[orient="vertical"] > splitter[collapse="after"] > grippy:hover:active,
-vbox > splitter[collapse="after"] > grippy:hover:active,
-box[orient="vertical"] > splitter[collapse="after"] > grippy:hover:active {
+splitter[collapse="after"][orient="vertical"] > grippy:hover:active {
   background-image: url("chrome://global/skin/splitter/grip-hrz-act.gif");
 }  
 
@@ -146,15 +130,11 @@ splitter[collapse="after"][state="collapsed"] > grippy {
 }
 
 /* horizontal grippies */
-window[orient="vertical"] > splitter[collapse="before"][state="collapsed"] > grippy,
-vbox > splitter[collapse="before"][state="collapsed"] > grippy,
-box[orient="vertical"] > splitter[collapse="before"][state="collapsed"] > grippy {
+splitter[collapse="before"][state="collapsed"][orient="vertical"] > grippy {
   background-image: url("chrome://global/skin/splitter/grip-hrz-after.gif");
 }  
 
-window[orient="vertical"] > splitter[collapse="after"][state="collapsed"] > grippy,
-vbox > splitter[collapse="after"][state="collapsed"] > grippy,
-box[orient="vertical"] > splitter[collapse="after"][state="collapsed"] > grippy {
+splitter[collapse="after"][state="collapsed"][orient="vertical"] > grippy {
   background-image: url("chrome://global/skin/splitter/grip-hrz-before.gif");
 }  
 
diff --git a/mozilla/xpfe/components/search/resources/internetresults.xul b/mozilla/xpfe/components/search/resources/internetresults.xul
index eb28159f8c6..997e79a9d33 100644
--- a/mozilla/xpfe/components/search/resources/internetresults.xul
+++ b/mozilla/xpfe/components/search/resources/internetresults.xul
@@ -156,7 +156,7 @@
 
   </tree>
 
-  <splitter id="results-splitter" persist="state" collapse="after" orient="vertical">
+  <splitter id="results-splitter" persist="state" collapse="after">
     <grippy/>
   </splitter>
   <hbox class="double-box-top" flex="1">
diff --git a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
index 82d160e95f9..9aab78baa41 100644
--- a/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
+++ b/mozilla/xpfe/components/sidebar/resources/sidebarOverlay.xul
@@ -163,7 +163,6 @@
   <!-- Splitter on the right of sidebar -->
   <splitter id="sidebar-splitter" collapse="before" persist="state hidden"
     class="chromeclass-extrachrome sidebar-splitter" align="center"
-    orient="vertical"
     onmouseup="SidebarFinishClick();">
     <grippy class="sidebar-splitter-grippy"
       onclick="SidebarCleanUpExpandCollapse();"/>